[MaxinOutThisSienna]

Hello All,

I've got a 2015 LE at 78 k and am in the process of doing a drain and fill every 50-100 miles to replace all of the trans fluid. I bought 10 qts. for this as a shop mentioned it takes that much for them to do a flush and fill.

I park the vehicle on a level surface and leave it to cool, making sure the vehicle is level by measuring the middle of the undercarriage where the pinch welds are joined. So far I've only been getting out about 1.5 qts. at each drain (only replacing that amount and following the procedure to get the van to the optimal temp for proper fill).

Does anyone know why I may not be getting out more than 1.5 qts. when I drain it? At this rate I'll need to do over 6 drain and fills to use the 10 qts.

Thanks for any insight!

Max

 

[greenskeeper]

You'll never get all of the old fluid out doing it this way. You are dilluting the old fluid with new at every change. I'll assume you are not removing the straw from the pan as that should get you to about 3 quarts per drain and fill.

Quick summary of how I did it on my van (full change)

1) drain fluid from pan (remove inner straw)

2) install inner straw and plug, add 3 quarts new ATF through fill hole

3) disconnect return line on transmission (coming from transmission cooler)

4) start van, measure fluid discharged, shut off van at 3 quart mark, will take approximately 30 seconds.

5) add 3 quarts new ATF through fill hole

6) repeat steps 4 & 5

7) at this point, you should see the fluid change from old to new on the return line. Shut off van, now only new fluid is in the system. Reconnect return line.

8) fill transmission (plug out) until fluid runs out of straw, measuring fluid at measuring temp with van in gear and level. Install plug when level is correct.

 

[jseyfert3]

I park the vehicle on a level surface and leave it to cool, making sure the vehicle is level by measuring the middle of the undercarriage where the pinch welds are joined. So far I've only been getting out about 1.5 qts. at each drain (only replacing that amount and following the procedure to get the van to the optimal temp for proper fill).

Does anyone know why I may not be getting out more than 1.5 qts. when I drain it? At this rate I'll need to do over 6 drain and fills to use the 10 qts.

First off, general recommendation for any oil changes is to drain while still warm. So for both engines and transmissions, drive till at normal temps, let cool until the exhaust and oil won't burn you but is still warm, then drain.

Second, as mentioned already, there are two parts to the transmission drain. Firstly, there's the main drain plug. But second, as you really need to be aware of, there is an overflow tube that sticks up through the bottom of the transmission pan. This overflow tube is used for setting the oil level. It needs to be removed (use a hex key) to drain all the fluid from the pan. If you don't remove this, all the fluid won't drain.

If you're removing this overflow tube and you are only getting 1.5 quarts out, you are underfilling the transmission. Refer to the factory service manual. I have this, but won't post here due to copyright reasons. I outlined the process for properly filling the transmission in my post here though, which is the procedure in the FSM.

You'll never get all of the old fluid out doing it this way. You are dilluting the old fluid with new at every change. I'll assume you are not removing the straw from the pan as that should get you to about 3 quarts per drain and fill.

Well, yes. You won't get all the old fluid out this way. But, do you need to? Most people say no. I decided to do some math on this.

First off, system capacity is 7 quarts of fluid. With a drain you can get 3 quarts. Some have said closer to 2.5 quarts. If you get 3, then three drain and fill cycles will replace 81% of the fluid. If 2.5, it's 73% of the fluid.

But of more interest to me was considering the average number of miles on the fluid. If you have a van with 100k miles, and the fluid has never been changed, then you do a drain and fill and that takes 3 quarts of fluid, you've replaced 43% of the fluid, so 57% is old. So the average number of miles on the fluid after mixing is 57,000 miles. Wow! A single drain and fill has left you with fluid that's roughly equivalent to fluid that's 57,000 miles old (0.57*100,000 + 0.43*0).

So say you do your first transmission fluid around 100k miles, as many used Sienna buyers here will do. You do a simple drain and fill, and the fluid is more or less equivalent to 57,000 mile fluid now. You decide to do a simple drain and fill once every 30,000 miles, which also seems to be commonly recommended here. Now, once you reach 130k miles, your fluid has an "equivalent" 87,000 miles. This considerably less mileage than the fluid had when you did your first one at 100,000 miles! But now you do your next drain and fill, and end up with "equivalent" mileage of...49,600 miles. Wow! The fluid is so young now! Repeat this and you get the following graph:

What you'll note is that even doing this simple drain and fill once every 30,000 miles, starting at 100,000 miles, the average miles on your fluid drastically drops.The average mileage of the fluid continues to drop over the next few change cycles, and by 310,000 miles, has evened out to somewhere around an average mileage on the transmission fluid of about 55,000 miles.

Now lets say we do a complete flush, without fluid mixing, every 100k miles. Well that's simple. Your average fluid mileage is simply going to be 50,000 miles. However, you'll end up spending a significant portion of the time with higher mileage fluid than the person who did the 30k simple drain and fill starting at 100k miles, because that person peaked at 100k miles (equivalent) and by their 3rd drain and fill at 160,000 miles they will never see above 80,000 miles (equivalent) on their transmission fluid again. Their equivalent average mileage is slightly higher, but on the flipside their fluid never gets as old either. Honestly after seeing the following graph, I'd prefer this, if comparing these two methodologies.

One last example. As an extreme, I heard one poster say "It takes me 15 minutes to do a drain/fill, so I just do one every oil change." Assuming a 10k oil change interval, that gets you very quickly to the point where your average transmission fluid mileage is just a bit over 18,000 miles.

Now, I note that @greenskeeper did a complete flush at ~31k miles. More power to you. Very few would suggest that interval is needed. If you continue doing full flush every 30k miles, your average transmission fluid mileage will be 15,000. This does work out slightly below the 10k drain/fill of 18,000 miles. Roughly the same amount of fluid used in either case, and the fluid is never getting old at all, so it's more a tradeoff of a quicker and easier drain/fill every 10k or a slightly more complicated flush every 30k.

What if I got my van new? For new vehicles, just imagine the curves starting out at 0 and working up to the steady state valves shown above graphs by roughly your 7th drain/fill.

What if my van has 150 k miles before I do anything, and I want to use 30k drain/fill cycles? If your van had 150k miles, then doing a drain fill at 150, 160, and 170k miles will result in fluid that has less average miles at the 170k mark than the steady state 30k drain/fill cycles. So change 3x at 10k or less interval, then switch to a 30k interval.

Opinion: It's my personal opinion from looking at these graphs that a 30k drain/flush is probably adequate, especially given that the manual only recommends 60k in cases of heavy loads, towing, or car-top carriers, and does not specify it otherwise. Still, we know to never change the fluid is a foolish recommendation and will likely lead to a transmission failure. It does seem the often repeated advice here of a drain/fill once every 30k miles will be sufficient for a decently long transmission life. Transmissions will wear out in time, regardless of how often the fluid is changed. More isn't always better. For example, I changed my Honda Pilot engine oil when the variable mileage maintenance minder told me to, which for my mostly highway driving was always a tick over 10,000 miles. I had multiple used oil analysis done by Blackstone Labs, and it always came back that the oil was in great shape still, and I could actually run more miles if I wanted to. More interesting though, was their newsletter where they revealed that their data they had accumulated showed that vehicles with some of the shortest change intervals (like 2000 miles) had more metals per mile (so more engine wear per mile) than cars with 6000 or 10,000 mile oil change intervals. While you'd need to statistically normalize this to filter out people that ran short changes but did lots of short trips with cold engines or lots of idling, it certainly is a strong finger backing up the "more is not always better" mantra.

Observation: Many here recommend not doing a flush, especially on older transmissions that may have never had any fluid change. While this seems to be largely based on what some say is a fallacy that flushing an old transmission kills it, the recommendation from those people to do multiple drain/flushes spaced apart and then proceed with something like one drain/flush, will, as the yellow line above shows, result in quickly reducing the average mileage of the fluid in your transmission.

Caveats: I could have messed something up with my math here, but I am reasonably confident it's correct. More importantly, "average mileage" as I'm using it here is not a 1-1 relationship when comparing to a drain/fill, as part of the fluid will be brand new, and part will be very old. Some portion as old as the vehicle is. Hence the term "average" is used. It is an average, but perhaps not a strictly equivalent average. However, I feel it's decently accurate, and in any case doing literally any sort of fluid change at all puts you above probably 95% of car owners.

 

[hangman]

I usually do not post like this, but unfortunately there is incorrect info in this post that, if someone were to follow this, it would cause damage to their vehicles so I had to make the following comments.

First off, general recommendation for any oil changes is to drain while still warm. So for both engines and transmissions, drive till at normal temps, let cool until the exhaust and oil won't burn you but is still warm, then drain.

This is not correct for the transmission fluid in the Sienna (or most vehicles for that matter). The trans fluid expands greatly based on temperature. The proper temp fluid change for the Sienna is between 104 to 114 degrees F, which is what the overflow tube is calibrated for. At operating normal temps as you suggest above, the fluid would have expanded greatly and the wrong volume would drain out of the over flow tube which will result in an under fill. There is a built-in function by jumping to pins in the OBD port that will show you when the correct temp has been reached for the fluid change. Running the car to operating temp is definitely not the correct process. Whether you wait for it to be cool to the touch or whatever other method.

If you're removing this overflow tube and you are only getting 1.5 quarts out, you are underfilling the transmission. Refer to the factory service manual. I have this, but won't post here due to copyright reasons. I outlined the process for properly filling the transmission in my post here though, which is the procedure in the FSM.

This is also not true. If you follow the correct procedures for changing the trans fluid and drain the fluid when it is cold, even with the removal of the overflow tube, you will have less than 2 qts coming out.

Now if you change it at operating temps, Toyota has a specific tool that the techs use to calculate the proper amount of fluid that drains out based on the fluid temp and that would show them how much fluid to replace as well. For more information on this, you can view the video here.

.
.
.


Also, if you want to DIY, here's the proper process,

As for the rest with math, I won't go into the details,....

Well, yes. You won't get all the old fluid out this way. But, do you need to? Most people say no. I decided to do some math on this.

First off, system capacity is 7 quarts of fluid. With a drain you can get 3 quarts. Some have said closer to 2.5 quarts. If you get 3, then three drain and fill cycles will replace 81% of the fluid. If 2.5, it's 73% of the fluid.

But of more interest to me was considering the average number of miles on the fluid. If you have a van with 100k miles, and the fluid has never been changed, then you do a drain and fill and that takes 3 quarts of fluid, you've replaced 43% of the fluid, so 57% is old. So the average number of miles on the fluid after mixing is 57,000 miles. Wow! A single drain and fill has left you with fluid that's roughly equivalent to fluid that's 57,000 miles old (0.57*100,000 + 0.43*0).

So say you do your first transmission fluid around 100k miles, as many used Sienna buyers here will do. You do a simple drain and fill, and the fluid is more or less equivalent to 57,000 mile fluid now. You decide to do a simple drain and fill once every 30,000 miles, which also seems to be commonly recommended here. Now, once you reach 130k miles, your fluid has an "equivalent" 87,000 miles. This considerably less mileage than the fluid had when you did your first one at 100,000 miles! But now you do your next drain and fill, and end up with "equivalent" mileage of...49,600 miles. Wow! The fluid is so young now! Repeat this and you get the following graph:
View attachment 58792
What you'll note is that even doing this simple drain and fill once every 30,000 miles, starting at 100,000 miles, the average miles on your fluid drastically drops.The average mileage of the fluid continues to drop over the next few change cycles, and by 310,000 miles, has evened out to somewhere around an average mileage on the transmission fluid of about 55,000 miles.

Now lets say we do a complete flush, without fluid mixing, every 100k miles. Well that's simple. Your average fluid mileage is simply going to be 50,000 miles. However, you'll end up spending a significant portion of the time with higher mileage fluid than the person who did the 30k simple drain and fill starting at 100k miles, because that person peaked at 100k miles (equivalent) and by their 3rd drain and fill at 160,000 miles they will never see above 80,000 miles (equivalent) on their transmission fluid again. Their equivalent average mileage is slightly higher, but on the flipside their fluid never gets as old either. Honestly after seeing the following graph, I'd prefer this, if comparing these two methodologies.
View attachment 58793
One last example. As an extreme, I heard one poster say "It takes me 15 minutes to do a drain/fill, so I just do one every oil change." Assuming a 10k oil change interval, that gets you very quickly to the point where your average transmission fluid mileage is just a bit over 18,000 miles.
View attachment 58795


Now, I note that @greenskeeper did a complete flush at ~31k miles. More power to you. Very few would suggest that interval is needed. If you continue doing full flush every 30k miles, your average transmission fluid mileage will be 15,000. This does work out slightly below the 10k drain/fill of 18,000 miles. Roughly the same amount of fluid used in either case, and the fluid is never getting old at all, so it's more a tradeoff of a quicker and easier drain/fill every 10k or a slightly more complicated flush every 30k.

What if I got my van new? For new vehicles, just imagine the curves starting out at 0 and working up to the steady state valves shown above graphs by roughly your 7th drain/fill.

What if my van has 150 k miles before I do anything, and I want to use 30k drain/fill cycles? If your van had 150k miles, then doing a drain fill at 150, 160, and 170k miles will result in fluid that has less average miles at the 170k mark than the steady state 30k drain/fill cycles. So change 3x at 10k or less interval, then switch to a 30k interval.

Opinion: It's my personal opinion from looking at these graphs that a 30k drain/flush is probably adequate, especially given that the manual only recommends 60k in cases of heavy loads, towing, or car-top carriers, and does not specify it otherwise. Still, we know to never change the fluid is a foolish recommendation and will likely lead to a transmission failure. It does seem the often repeated advice here of a drain/fill once every 30k miles will be sufficient for a decently long transmission life. Transmissions will wear out in time, regardless of how often the fluid is changed. More isn't always better. For example, I changed my Honda Pilot engine oil when the variable mileage maintenance minder told me to, which for my mostly highway driving was always a tick over 10,000 miles. I had multiple used oil analysis done by Blackstone Labs, and it always came back that the oil was in great shape still, and I could actually run more miles if I wanted to. More interesting though, was their newsletter where they revealed that their data they had accumulated showed that vehicles with some of the shortest change intervals (like 2000 miles) had more metals per mile (so more engine wear per mile) than cars with 6000 or 10,000 mile oil change intervals. While you'd need to statistically normalize this to filter out people that ran short changes but did lots of short trips with cold engines or lots of idling, it certainly is a strong finger backing up the "more is not always better" mantra.

Observation: Many here recommend not doing a flush, especially on older transmissions that may have never had any fluid change. While this seems to be largely based on what some say is a fallacy that flushing an old transmission kills it, the recommendation from those people to do multiple drain/flushes spaced apart and then proceed with something like one drain/flush, will, as the yellow line above shows, result in quickly reducing the average mileage of the fluid in your transmission.

Caveats: I could have messed something up with my math here, but I am reasonably confident it's correct. More importantly, "average mileage" as I'm using it here is not a 1-1 relationship when comparing to a drain/fill, as part of the fluid will be brand new, and part will be very old. Some portion as old as the vehicle is. Hence the term "average" is used. It is an average, but perhaps not a strictly equivalent average. However, I feel it's decently accurate, and in any case doing literally any sort of fluid change at all puts you above probably 95% of car owners.

First off, general recommendation for any oil changes is to drain while still warm. So for both engines and transmissions, drive till at normal temps, let cool until the exhaust and oil won't burn you but is still warm, then drain.

Second, as mentioned already, there are two parts to the transmission drain. Firstly, there's the main drain plug. But second, as you really need to be aware of, there is an overflow tube that sticks up through the bottom of the transmission pan. This overflow tube is used for setting the oil level. It needs to be removed (use a hex key) to drain all the fluid from the pan. If you don't remove this, all the fluid won't drain.

If you're removing this overflow tube and you are only getting 1.5 quarts out, you are underfilling the transmission. Refer to the factory service manual. I have this, but won't post here due to copyright reasons. I outlined the process for properly filling the transmission in my post here though, which is the procedure in the FSM.


Well, yes. You won't get all the old fluid out this way. But, do you need to? Most people say no. I decided to do some math on this.

First off, system capacity is 7 quarts of fluid. With a drain you can get 3 quarts. Some have said closer to 2.5 quarts. If you get 3, then three drain and fill cycles will replace 81% of the fluid. If 2.5, it's 73% of the fluid.

But of more interest to me was considering the average number of miles on the fluid. If you have a van with 100k miles, and the fluid has never been changed, then you do a drain and fill and that takes 3 quarts of fluid, you've replaced 43% of the fluid, so 57% is old. So the average number of miles on the fluid after mixing is 57,000 miles. Wow! A single drain and fill has left you with fluid that's roughly equivalent to fluid that's 57,000 miles old (0.57*100,000 + 0.43*0).

So say you do your first transmission fluid around 100k miles, as many used Sienna buyers here will do. You do a simple drain and fill, and the fluid is more or less equivalent to 57,000 mile fluid now. You decide to do a simple drain and fill once every 30,000 miles, which also seems to be commonly recommended here. Now, once you reach 130k miles, your fluid has an "equivalent" 87,000 miles. This considerably less mileage than the fluid had when you did your first one at 100,000 miles! But now you do your next drain and fill, and end up with "equivalent" mileage of...49,600 miles. Wow! The fluid is so young now! Repeat this and you get the following graph:
View attachment 58792
What you'll note is that even doing this simple drain and fill once every 30,000 miles, starting at 100,000 miles, the average miles on your fluid drastically drops.The average mileage of the fluid continues to drop over the next few change cycles, and by 310,000 miles, has evened out to somewhere around an average mileage on the transmission fluid of about 55,000 miles.

Now lets say we do a complete flush, without fluid mixing, every 100k miles. Well that's simple. Your average fluid mileage is simply going to be 50,000 miles. However, you'll end up spending a significant portion of the time with higher mileage fluid than the person who did the 30k simple drain and fill starting at 100k miles, because that person peaked at 100k miles (equivalent) and by their 3rd drain and fill at 160,000 miles they will never see above 80,000 miles (equivalent) on their transmission fluid again. Their equivalent average mileage is slightly higher, but on the flipside their fluid never gets as old either. Honestly after seeing the following graph, I'd prefer this, if comparing these two methodologies.
View attachment 58793
One last example. As an extreme, I heard one poster say "It takes me 15 minutes to do a drain/fill, so I just do one every oil change." Assuming a 10k oil change interval, that gets you very quickly to the point where your average transmission fluid mileage is just a bit over 18,000 miles.
View attachment 58795


Now, I note that @greenskeeper did a complete flush at ~31k miles. More power to you. Very few would suggest that interval is needed. If you continue doing full flush every 30k miles, your average transmission fluid mileage will be 15,000. This does work out slightly below the 10k drain/fill of 18,000 miles. Roughly the same amount of fluid used in either case, and the fluid is never getting old at all, so it's more a tradeoff of a quicker and easier drain/fill every 10k or a slightly more complicated flush every 30k.

What if I got my van new? For new vehicles, just imagine the curves starting out at 0 and working up to the steady state valves shown above graphs by roughly your 7th drain/fill.

What if my van has 150 k miles before I do anything, and I want to use 30k drain/fill cycles? If your van had 150k miles, then doing a drain fill at 150, 160, and 170k miles will result in fluid that has less average miles at the 170k mark than the steady state 30k drain/fill cycles. So change 3x at 10k or less interval, then switch to a 30k interval.

Opinion: It's my personal opinion from looking at these graphs that a 30k drain/flush is probably adequate, especially given that the manual only recommends 60k in cases of heavy loads, towing, or car-top carriers, and does not specify it otherwise. Still, we know to never change the fluid is a foolish recommendation and will likely lead to a transmission failure. It does seem the often repeated advice here of a drain/fill once every 30k miles will be sufficient for a decently long transmission life. Transmissions will wear out in time, regardless of how often the fluid is changed. More isn't always better. For example, I changed my Honda Pilot engine oil when the variable mileage maintenance minder told me to, which for my mostly highway driving was always a tick over 10,000 miles. I had multiple used oil analysis done by Blackstone Labs, and it always came back that the oil was in great shape still, and I could actually run more miles if I wanted to. More interesting though, was their newsletter where they revealed that their data they had accumulated showed that vehicles with some of the shortest change intervals (like 2000 miles) had more metals per mile (so more engine wear per mile) than cars with 6000 or 10,000 mile oil change intervals. While you'd need to statistically normalize this to filter out people that ran short changes but did lots of short trips with cold engines or lots of idling, it certainly is a strong finger backing up the "more is not always better" mantra.

Observation: Many here recommend not doing a flush, especially on older transmissions that may have never had any fluid change. While this seems to be largely based on what some say is a fallacy that flushing an old transmission kills it, the recommendation from those people to do multiple drain/flushes spaced apart and then proceed with something like one drain/flush, will, as the yellow line above shows, result in quickly reducing the average mileage of the fluid in your transmission.

Caveats: I could have messed something up with my math here, but I am reasonably confident it's correct. More importantly, "average mileage" as I'm using it here is not a 1-1 relationship when comparing to a drain/fill, as part of the fluid will be brand new, and part will be very old. Some portion as old as the vehicle is. Hence the term "average" is used. It is an average, but perhaps not a strictly equivalent average. However, I feel it's decently accurate, and in any case doing literally any sort of fluid change at all puts you above probably 95% of car owners.

 

[jseyfert3]

This is not correct for the transmission fluid in the Sienna (or most vehicles for that matter). The trans fluid expands greatly based on temperature. The proper temp fluid change for the Sienna is between 104 to 114 degrees F, which is what the overflow tube is calibrated for. At operating normal temps as you suggest above, the fluid would have expanded greatly and the wrong volume would drain out of the over flow tube which will result in an under fill. There is a built-in function by jumping to pins in the OBD port that will show you when the correct temp has been reached for the fluid change. Running the car to operating temp is definitely not the correct process. Whether you wait for it to be cool to the touch or whatever other method.

I was referring to a drain to dump the fluid, not the overflow drain process to set the fluid level. Because this drain is what the OP was asking about, so that’s what I was answering.

Everything I’ve read for oil changes says to drain with the oil still warm from operation, so it drains faster, more fully, and junk suspended in the oil doesn’t have a lot of time to settle out.

The drain for setting fluid level after refilling is very temperature specific, which I outlined in my linked post. Draining the transmission oil sith the overflow tube to set the level with the trans at the incorrect temp and not engaging engine idle speed control as outlined in the factory service manual will lead to over or under filling that can damage the transmission. 100% agree with you here.

This is also not true. If you follow the correct procedures for changing the trans fluid and drain the fluid when it is cold, even with the removal of the overflow tube, you will have less than 2 qts coming out.

Now if you change it at operating temps, Toyota has a specific tool that the techs use to calculate the proper amount of fluid that drains out based on the fluid temp and that would show them how much fluid to replace as well. For more information on this, you can view the video here.

Fair enough. If that’s what it is, that’s what it is. I haven’t personally changed it yet myself. But I did refer to the FSM, which doesn’t list fluid volume drained from the drain plug, but does list 3 quarts lost if dropping the pan. It seems odd that the drain plug would drain only half the oil in the pan. I was also basing it on multiple posts I’ve read here, where people definitely reported more than 2 quarts of oil drained. I think 2.5 quarts seemed about average, which seems more reasonable if the pan holds 3 quarts.

I plan to do this myself soon. So I will measure and report back what I got out.

Also I generally dislike video repair videos. With rare (but glorious) exceptions, they are terribly edited, with way too much unnecessary info and footage of things being done. So I generally always avoid watching them.

I do, on the other hand, value correct information. So I have purchased and refer to the official Toyota Factory Service Manual when performing work on my vehicle. I have all the FSM that pertains to the transmission downloaded on my computer. Again, straight from Toyota, not some 3rd party site. My linked post on how to set the transmission fluid level is 100% based off reading the FSM, not based on info read here, a video, or another 3rd party site.

Anyone else can purchase a subscription and download what they’d like for their model year van (or any other Toyota vehicle they own). I generally get the 2-day subscription for $20 and download everything relevant to the project I’m working on at the time, as well as parts relating to work I think I’ll need in the future. Downloads stay with you forever and don’t expire. You could, if you had patience and a weekend to burn, download the entire FSM for the van in a 2-day subscription and have it forever. techinfo.toyota.com

 

[hangman]

The reason the FSM states 3 qts is because the FSB is probably referring to dropping the pan as you mentioned. But for a drain and fill, you cannot fully empty the pan. The reason for this is that the drain plug is set in a metal molding that holds the tube that is raised so, even when you remove the calibrated level tube, the metal molding that holds it still is above the bottom of the pan level. I have attached a pictrue of the pan that shows this and explains why you cannot fully empty the pan from a drain and fill.

 

[jseyfert3]

Yes, it is for a pan drop, as I stated.

Thanks for the picture, that makes a lot of sense why so much fluid would be left. Toyota really made it difficult to change the fluid.

I did some searching and I’m still seeing closer to 2-2.25 quarts drained here on the forum. What’s not clear is who is properly filling at the right temps, with engine idle speed control engaged, no leaks, etc. Engine idle speed control is something I’ve never seen someone on the forum mention, but the manual is very specific that you need to engage engine idle speed control to properly set transmission fluid level.

Only draining 1.5-2 quarts will change the numbers on my previous graphs a lot.

I’m planning on checking my fluid level before draining, then carefully measuring the fluid I get when I do my drain for future reference.

I’m also thinking I may send some samples off to Blackstone Laboratories and watch how the fluid wears over time. I’ll start my own thread though and stop spamming the OP.

 

[q0987]

This is also not true. If you follow the correct procedures for changing the trans fluid and drain the fluid when it is cold, even with the removal of the overflow tube, you will have less than 2 qts coming out.

I had the same experience indicated by hangman.
When I drained the ATF after resting the car overnight, you will only get less than 2 quarts of oil out.

Best

 

[greenskeeper]

First off, general recommendation for any oil changes is to drain while still warm. So for both engines and transmissions, drive till at normal temps, let cool until the exhaust and oil won't burn you but is still warm, then drain.

Second, as mentioned already, there are two parts to the transmission drain. Firstly, there's the main drain plug. But second, as you really need to be aware of, there is an overflow tube that sticks up through the bottom of the transmission pan. This overflow tube is used for setting the oil level. It needs to be removed (use a hex key) to drain all the fluid from the pan. If you don't remove this, all the fluid won't drain.

If you're removing this overflow tube and you are only getting 1.5 quarts out, you are underfilling the transmission. Refer to the factory service manual. I have this, but won't post here due to copyright reasons. I outlined the process for properly filling the transmission in my post here though, which is the procedure in the FSM.


Well, yes. You won't get all the old fluid out this way. But, do you need to? Most people say no. I decided to do some math on this.

First off, system capacity is 7 quarts of fluid. With a drain you can get 3 quarts. Some have said closer to 2.5 quarts. If you get 3, then three drain and fill cycles will replace 81% of the fluid. If 2.5, it's 73% of the fluid.

But of more interest to me was considering the average number of miles on the fluid. If you have a van with 100k miles, and the fluid has never been changed, then you do a drain and fill and that takes 3 quarts of fluid, you've replaced 43% of the fluid, so 57% is old. So the average number of miles on the fluid after mixing is 57,000 miles. Wow! A single drain and fill has left you with fluid that's roughly equivalent to fluid that's 57,000 miles old (0.57*100,000 + 0.43*0).

So say you do your first transmission fluid around 100k miles, as many used Sienna buyers here will do. You do a simple drain and fill, and the fluid is more or less equivalent to 57,000 mile fluid now. You decide to do a simple drain and fill once every 30,000 miles, which also seems to be commonly recommended here. Now, once you reach 130k miles, your fluid has an "equivalent" 87,000 miles. This considerably less mileage than the fluid had when you did your first one at 100,000 miles! But now you do your next drain and fill, and end up with "equivalent" mileage of...49,600 miles. Wow! The fluid is so young now! Repeat this and you get the following graph:
View attachment 58792
What you'll note is that even doing this simple drain and fill once every 30,000 miles, starting at 100,000 miles, the average miles on your fluid drastically drops.The average mileage of the fluid continues to drop over the next few change cycles, and by 310,000 miles, has evened out to somewhere around an average mileage on the transmission fluid of about 55,000 miles.

Now lets say we do a complete flush, without fluid mixing, every 100k miles. Well that's simple. Your average fluid mileage is simply going to be 50,000 miles. However, you'll end up spending a significant portion of the time with higher mileage fluid than the person who did the 30k simple drain and fill starting at 100k miles, because that person peaked at 100k miles (equivalent) and by their 3rd drain and fill at 160,000 miles they will never see above 80,000 miles (equivalent) on their transmission fluid again. Their equivalent average mileage is slightly higher, but on the flipside their fluid never gets as old either. Honestly after seeing the following graph, I'd prefer this, if comparing these two methodologies.
View attachment 58793
One last example. As an extreme, I heard one poster say "It takes me 15 minutes to do a drain/fill, so I just do one every oil change." Assuming a 10k oil change interval, that gets you very quickly to the point where your average transmission fluid mileage is just a bit over 18,000 miles.
View attachment 58795


Now, I note that @greenskeeper did a complete flush at ~31k miles. More power to you. Very few would suggest that interval is needed. If you continue doing full flush every 30k miles, your average transmission fluid mileage will be 15,000. This does work out slightly below the 10k drain/fill of 18,000 miles. Roughly the same amount of fluid used in either case, and the fluid is never getting old at all, so it's more a tradeoff of a quicker and easier drain/fill every 10k or a slightly more complicated flush every 30k.

What if I got my van new? For new vehicles, just imagine the curves starting out at 0 and working up to the steady state valves shown above graphs by roughly your 7th drain/fill.

What if my van has 150 k miles before I do anything, and I want to use 30k drain/fill cycles? If your van had 150k miles, then doing a drain fill at 150, 160, and 170k miles will result in fluid that has less average miles at the 170k mark than the steady state 30k drain/fill cycles. So change 3x at 10k or less interval, then switch to a 30k interval.

Opinion: It's my personal opinion from looking at these graphs that a 30k drain/flush is probably adequate, especially given that the manual only recommends 60k in cases of heavy loads, towing, or car-top carriers, and does not specify it otherwise. Still, we know to never change the fluid is a foolish recommendation and will likely lead to a transmission failure. It does seem the often repeated advice here of a drain/fill once every 30k miles will be sufficient for a decently long transmission life. Transmissions will wear out in time, regardless of how often the fluid is changed. More isn't always better. For example, I changed my Honda Pilot engine oil when the variable mileage maintenance minder told me to, which for my mostly highway driving was always a tick over 10,000 miles. I had multiple used oil analysis done by Blackstone Labs, and it always came back that the oil was in great shape still, and I could actually run more miles if I wanted to. More interesting though, was their newsletter where they revealed that their data they had accumulated showed that vehicles with some of the shortest change intervals (like 2000 miles) had more metals per mile (so more engine wear per mile) than cars with 6000 or 10,000 mile oil change intervals. While you'd need to statistically normalize this to filter out people that ran short changes but did lots of short trips with cold engines or lots of idling, it certainly is a strong finger backing up the "more is not always better" mantra.

Observation: Many here recommend not doing a flush, especially on older transmissions that may have never had any fluid change. While this seems to be largely based on what some say is a fallacy that flushing an old transmission kills it, the recommendation from those people to do multiple drain/flushes spaced apart and then proceed with something like one drain/flush, will, as the yellow line above shows, result in quickly reducing the average mileage of the fluid in your transmission.

Caveats: I could have messed something up with my math here, but I am reasonably confident it's correct. More importantly, "average mileage" as I'm using it here is not a 1-1 relationship when comparing to a drain/fill, as part of the fluid will be brand new, and part will be very old. Some portion as old as the vehicle is. Hence the term "average" is used. It is an average, but perhaps not a strictly equivalent average. However, I feel it's decently accurate, and in any case doing literally any sort of fluid change at all puts you above probably 95% of car owners.

It took 10.5 quarts when I changed the ATF in the process I stated earlier.

The dillution you speak of is not an accurate representation of what actually occurs. You still have old fluid with 100k miles on it no matter how many times you change 3 quarts at a time, circulating in the transmission. "Average fluid miles" means nothing as ATF degrades over time depending on transmission temp.

Is it better than not changing it at all... yes.

I'd rather change all of the fluid out and be done with it, knowing that it was done correctly.

A complete change resets the fluid mileage to ZERO, not a divisional number as you stated.

Additionally if you don't know the temperature of the ATF fluid when "topping off" it's possible that you have overfilled or underfilled the transmission, which is far worse than leaving the "lifetime" fluid in there.

The procedure I did really isn't all that complicated, and it's a way to fully change the fluid from old to new. I service all my transmissions (auto or manual) every 30k miles, never had a transmission failure...yet. Highest mile manual transmission has 266k on it... highest automatic transmission has 216k on it.

 

[greenskeeper]

Yes, it is for a pan drop, as I stated.

Thanks for the picture, that makes a lot of sense why so much fluid would be left. Toyota really made it difficult to change the fluid.

I did some searching and I’m still seeing closer to 2-2.25 quarts drained here on the forum. What’s not clear is who is properly filling at the right temps, with engine idle speed control engaged, no leaks, etc. Engine idle speed control is something I’ve never seen someone on the forum mention, but the manual is very specific that you need to engage engine idle speed control to properly set transmission fluid level.

Only draining 1.5-2 quarts will change the numbers on my previous graphs a lot.

I’m planning on checking my fluid level before draining, then carefully measuring the fluid I get when I do my drain for future reference.

I’m also thinking I may send some samples off to Blackstone Laboratories and watch how the fluid wears over time. I’ll start my own thread though and stop spamming the OP.

transmission fluid level is checked with the drain plug removed, with the transmission in gear, at an ATF temp between 108-113F, topped off until fluid runs out of the straw and stops.

 

[jseyfert3]

This is also not true. If you follow the correct procedures for changing the trans fluid and drain the fluid when it is cold, even with the removal of the overflow tube, you will have less than 2 qts coming out.
<snip>
Also, if you want to DIY, here's the proper process,
<Link to Car Care Nut's video>

I scanned the video. Good stuff. And exactly what I said in my linked post. The only thing I saw he missed clarifying was to put the car back in park after you do the shifting to activate temp monitoring.

What I did note was that he drained just a tad under 2.5 quarts, not less that 2 quarts, and from what I can find the Camry he was demonstrating has the same transmission as the Sienna. Different front driveaxles could change that number though.

It took 10.5 quarts when I changed the ATF in the process I stated earlier.

The dillution you speak of is not an accurate representation of what actually occurs. You still have old fluid with 100k miles on it no matter how many times you change 3 quarts at a time, circulating in the transmission. "Average fluid miles" means nothing as ATF degrades over time depending on transmission temp.

Is it better than not changing it at all... yes.

I'd rather change all of the fluid out and be done with it, knowing that it was done correctly.

A complete change resets the fluid mileage to ZERO, not a divisional number as you stated.

Additionally if you don't know the temperature of the ATF fluid when "topping off" it's possible that you have overfilled or underfilled the transmission, which is far worse than leaving the "lifetime" fluid in there.

The procedure I did really isn't all that complicated, and it's a way to fully change the fluid from old to new. I service all my transmissions (auto or manual) every 30k miles, never had a transmission failure...yet. Highest mile manual transmission has 266k on it... highest automatic transmission has 216k on it.

I did mention that it's not going to be a completely straight comparison, but it should be pretty close to the ballpark. As the oil ages, several things happen. The viscosity of the oil can go down, the TAN (total acid number) goes up, and particulates build up in the oil, additives are used up, etc.

These are all things that will reduce with a partial oil change. If you have X amount of particulates, suspended evenly through the oil, then changing 35% of the oil (2.5 quarts in 7), will drop the particulates by 35%. Assuming the same driving style and temp, particulate build-up should be pretty linear with miles. So if you have a transmission with new fluid and no particulates, and drive for some period of time, 30,000 miles in your case, then you'll have 30,000 miles worth of particulate build-up. This number increased over time linearly. Dumping all the fluid will reduce this to effectively zero. But on average (over the lifespan unless it meets an early death) the transmission will have 15,000 miles worth of particulates in the oil. Half the time, it'll have less than the 15,000 miles worth, half the time, more than 15,000 miles worth. We can all agree that particulates in oil are bad I think, as they lead to extra wear. But doing a partial drain and fill of whatever quantity at whatever interval that works out to leave tthe oil with an average concentration of 15,000 miles of particulates should be exactly the same, over the lifespan of the car, as a complete fluid replacement every 30,000 miles. In fact, it may be better, as you don't ever reach the 30,000 mile level of contaminates ever, but stay much closer to the 15,000 mile level. Of course, the flipside is that you also don't get the 15,000 mile intervals where the particulate level is zero. But I really think the net result is going to work out pretty close to exactly the same.

Viscosity, TAN, additive usage may not be completely linear, but overall the same concept applies. Mixing an oil with a cSt viscosity at 100 °C of 12 with one of 15 results in an oil with a cSt viscosity of 13.4, almost exactly what an average of the two numbers (13.5) would yield. So if the viscosity drops over time, mixing in new oil will result in an oil with essentially the same viscosity. So if new oil was 15, and was 12 when changed at 30,000 miles, your average viscosity was 13.5. And doing the same partial oil changes for the "equivalent average mileage" will likewise yield the same average oil viscosity. Again though, with much less "peaking", as you'd never reach 12 nor ever get to 15, but your average would be pretty darn close to the average of the complete drain and fill.

Similarly, TAN won't get as high, nor be as low, additives won't be as high, nor be as low, etc.

It very much should be the case that partial fluid changes, when calculated out with appropriate drain values (my 3 quarts used to make those graphs is wrong, but the number that needs to be used is not the drain amount of 2 quarts or whatever it is, but the drain plus slight overfill amounts. So if 2 is drained and 2.5 quarts is added, then drained to overflow, 2.5 needs to be used for these numbers) and change intervals, will yield close to the same average fluid properties. Total drains are not needed. This is simply a textbook fluid mixing problem.

Whether one finds it easier to remove hoses to do a complete flush, or simply does a partial drain and fill, doesn't matter. Only the relative frequencies of each, based on calculations with the % fluid changed.

transmission fluid level is checked with the drain plug removed, with the transmission in gear, at an ATF temp between 108-113F, topped off until fluid runs out of the straw and stops.

No. It's measured with the transmission in park.

What follows is the relevant portion of my linked post, which again is the Toyota FSM procedure, since several comments seem to imply I don't know how to set the fluid level properly, despite linking the post multiple times. This procedure is the same as that outlined by the video made by Car Care Nut that @hangman posted earlier (except that video didn't specifically say to put it in park, but if you watch the video it's clearly in park as the vehicle is on a lift and the front drive wheels are not rotating):

1. Connect pins 4 & 13 of the OBD connector.
2. Depress brake pedal and start engine.
3. Slowly move shift lever from P to D, then back to P (slowly, to circulate the fluid through each part of the transmission).
4. While watching gearshift indicator, move shift lever from D to N and back at 1.5 second intervals for 6 seconds or more. This will cause vehicle to enter fluid temp detection mode.
5. Check that the D shift indicator comes on for 2 seconds.
6. Move shift lever from N to P.
7. Release brake pedal.
8. Remove jumper from OBD connector. Removing jumper activates engine idle speed control
9. Allow engine to idle until the D shift indicator comes on again
   1. Below temp the D indicator is off
   2. At temp (104 to 113 °F) the D indicator is on
   3. Above temp the D indicator is blinking
10. Remove the overflow plug
11. If fluid overflows
    1. Wait until fluid slows and only drips come out
    2. Remove fluid fill plug
12. If fluid does not overflow
    1. Remove fluid fill plug
    2. Add fluid through refill until fluid comes out of the overflow plug hole
    3. Wait until fluid slows and only drips come out
13. Install overflow plug
14. Install refill plug
15. Turn off engine

Step 11.2 seems unnecessary, but it's in the FSM so I've included it here for the sake of completeness.

 

[OnTheRoadAgain]

Don't drain it all out unless you want a new transmission. Even if it's done through multiple times.

I did mine this past summer, only 1.5 quart came out. I did it cause my van hit 65k and it's over 10 yrs old. I don't plan on doing this for another 60k/10yrs per car Care nut's recommendation.

 

[dave1968]

I park the vehicle on a level surface and leave it to cool, making sure the vehicle is level by measuring the middle of the undercarriage where the pinch welds are joined. So far I've only been getting out about 1.5 qts. at each drain (only replacing that amount and following the procedure to get the van to the optimal temp for proper fill).

2014 XLE FWD here and I only get out 1.5 quarts each time with the van level and cool, just like the OP. After removing the straw to drain the pan, I reinsert the straw and drain plug, then add 2 quarts. I use the OBD pin 4 & 13 jumper procedure to determine the transmission temp at which time .5 quarts excess drains out so I have to believe my process is correct. I did this 3x over a couple weekends in order to get the fluid back a decently red hue.

One thing I've noticed from watching videos on this, is that some Toyotas have a green straw while mine is red. The green straw appears to be a bit longer, which may explain why some folks get 2+ quarts out. I've been unable to find any real information on why there are 2 colors so if anyone has insights on this, please advise.

 

[sbihue]

One thing I've noticed from watching videos on this, is that some Toyotas have a green straw while mine is red. The green straw appears to be a bit longer, which may explain why some folks get 2+ quarts out. I've been unable to find any real information on why there are 2 colors so if anyone has insights on this, please advise.

Could be. Mine has a red straw and the 1st/initial drain was around 1.3 Qts on a cold engine. Having read the posts earlier I was thinking it was low from the factory as I was also expecting at-least 1.5 qts. However after 4 more refills over the next few days, the drained qty was just about 1.4 Qts

 

[MaxinOutThisSienna]

Hi all, thanks so much to everyone for your time in crafting detailed responses. I was most worried that I wasn't getting enough fluid out at each drain, and feel better seeing that I'm getting about the average amount out.

One question: it seems like the general advice is to not replace all of the fluid either by flush or multiple drain and fills. If not, how many qts. do you think we should be draining/ filling every 30k? So far in my two drain and fills I've replaced ~3 qts.

Thanks again everyone!

Max

 

[OnTheRoadAgain]

Hi all, thanks so much to everyone for your time in crafting detailed responses. I was most worried that I wasn't getting enough fluid out at each drain, and feel better seeing that I'm getting about the average amount out.

One question: it seems like the general advice is to not replace all of the fluid either by flush or multiple drain and fills. If not, how many qts. do you think we should be draining/ filling every 30k? So far in my two drain and fills I've replaced ~3 qts.

Thanks again everyone!

Max

2. I bought 3 so I have an extra qrt just sitting around.

60k would be my routine. Not even 30. At least for me.

 

[greenskeeper]

Trying to wrap my head around the idea that a partial fluid change is better than a complete change..."average fluid miles" doesn't work in reality since automotive fluids breakdown as the miles pile up.

 

[hangman]

Trying to wrap my head around the idea that a partial fluid change is better than a complete change..."average fluid miles" doesn't work in reality since automotive fluids breakdown as the miles pile up.

The difference here is that you are thinking in terms of engine “oil” and not automatic transmission “fluid”.
The goal of engine oil, is ultimate protection of the metal parts ( as much friction reduction as possible).
Hence you always want brand new oil.
Automatic Transmission fluid is not really designed with ultimate friction reduction in mind. Of course It is designed to lubricate to protect the internals and act as a hydraulic fluid, but unlike an oil, it’s goal is not ultimate friction reduction.
In fact, the automatic transmissions need friction for the clutch packs to work. As the clutch wears of, the clutch material is suspended in the fluid, and is what still provides the “friction” required for the clutches to continue to work.
This is why you hear stories of flushing very high milage transmissions that have never had a fluid change and the transmissions start to slip afterwards. So flushing away all the clutch material in the old fluid can kill a transmission.
But the trans fluid does break down overtime from use and heat, so you do want to keep the fluid from completely breaking down. This is where to recommended partial fluid change comes in. You don’t want to completely flush the trans and lose all the friction material in the old fluid, but you also want to refresh some of the fluid.

Now for manual transmissions, they do not use clutch packs like an automatic, they jus have gears. The clutch that seperate s the trans from the engine is seperate and not part of the trans internal gears. To protect manual transmission, a gear “oil” is used to protect the gears from friction instead of automatic transmission “fluid”.

 

[OnTheRoadAgain]

The difference here is that you are thinking in terms of engine “oil” and not automatic transmission “fluid”.
The goal of engine oil, is ultimate protection of the metal parts ( as much friction reduction as possible).
Hence you always want brand new oil.
Automatic Transmission fluid is not really designed with ultimate friction reduction in mind. Of course It is designed to lubricate to protect the internals and act as a hydraulic fluid, but unlike an oil, it’s goal is not ultimate friction reduction.
In fact, the automatic transmissions need friction for the clutch packs to work. As the clutch wears of, the clutch material is suspended in the fluid, and is what still provides the “friction” required for the clutches to continue to work.
This is why you hear stories of flushing very high milage transmissions that have never had a fluid change and the transmissions start to slip afterwards. So flushing away all the clutch material in the old fluid can kill a transmission.
But the trans fluid does break down overtime from use and heat, so you do want to keep the fluid from completely breaking down. This is where to recommended partial fluid change comes in. You don’t want to completely flush the trans and lose all the friction material in the old fluid, but you also want to refresh some of the fluid.

Now for manual transmissions, they do not use clutch packs like an automatic, they jus have gears. The clutch that seperate s the trans from the engine is seperate and not part of the trans internal gears. To protect manual transmission, a gear “oil” is used to protect the gears from friction instead of automatic transmission “fluid”.

Well said. Yes don't flush. Unless You're ready for a new transmission.

 

[greenskeeper]

The difference here is that you are thinking in terms of engine “oil” and not automatic transmission “fluid”.
The goal of engine oil, is ultimate protection of the metal parts ( as much friction reduction as possible).
Hence you always want brand new oil.
Automatic Transmission fluid is not really designed with ultimate friction reduction in mind. Of course It is designed to lubricate to protect the internals and act as a hydraulic fluid, but unlike an oil, it’s goal is not ultimate friction reduction.
In fact, the automatic transmissions need friction for the clutch packs to work. As the clutch wears of, the clutch material is suspended in the fluid, and is what still provides the “friction” required for the clutches to continue to work.
This is why you hear stories of flushing very high milage transmissions that have never had a fluid change and the transmissions start to slip afterwards. So flushing away all the clutch material in the old fluid can kill a transmission.
But the trans fluid does break down overtime from use and heat, so you do want to keep the fluid from completely breaking down. This is where to recommended partial fluid change comes in. You don’t want to completely flush the trans and lose all the friction material in the old fluid, but you also want to refresh some of the fluid.

Now for manual transmissions, they do not use clutch packs like an automatic, they jus have gears. The clutch that seperate s the trans from the engine is seperate and not part of the trans internal gears. To protect manual transmission, a gear “oil” is used to protect the gears from friction instead of automatic transmission “fluid”.

"As the clutch wears of, the clutch material is suspended in the fluid, and is what still provides the “friction” required for the clutches to continue to work."

Clearly you aren't a mechanic... that's ok. If Toyota (and other manufacturers) didn't purposely eliminate an easy way to service the transmission, we wouldn't be having this conversation.

"This is why you hear stories of flushing very high milage transmissions that have never had a fluid change and the transmissions start to slip afterwards. So flushing away all the clutch material in the old fluid can kill a transmission."

The sludge and build-up from not changing the ATF dislodges and ruins the valve body... if that was the case, wouldn't there be a need for "clutch material additive" when changing ATF fluid?