Sienna 2000 transmission fluid change related question

[aks2000]

I have a Sienna 2000 XLE with 168000 miles on it. I bought it new and it still runs absolutely fine.

Her transmission and differential were drained and refilled at 90000 miles service by Toyota dealership in 2005. The pan was also dropped and cleaned.

Since then, I started changing transmission fluid myself every 15000 miles / year by sucking out the fluid from dipstick using a 12v vacuum pump and adding back the new fluid in the same amount that came out. I usually get 2.5 qt out this way. Since I don't get complete fluid out this way, I do this every year to keep the fluid close to fresh if not absolutely fresh. The differential doesn't get drained (or sucked) in this process.

My questions are

1. Since transmission and differential share the feed, does differential fluid also get refreshed by means of circulation/diffusion as the car is being driven ? OR it keeps the fluid in an isolated cavity after filling it the first time ? I may have to drain differential if later is the case.

2. Is this way of changing the fluid OK ? I am doing it for last 4-5 years and the van seems to be running fine until now at least.

3. Is drooping the pan necessary ?

Thanks in advance for your responses.

[nitroman]

I'd like to know the answer to these as well, since I'm planning on starting to do something similar for my 2007 LE. So if some more knowledgeable gurus can answer that would be great. Though by reading through the other forums, I noticed a few things regarding what you are doing:

1) Most people that drain through the plug get about 4 qts out, and they say that's about half of the total. Since you only drain 2.5/8 qts, that's only about 30% of new stuff, and 70% old stuff. Initially it should be fine but I'm not sure if that would be enough as the years go by. The last time you did it, when you looked at the fluid what did it look like compared to new fluid? Also did it smell burnt or something.
EDIT: Actually I just saw in another post that says there's 12 qts of ATF fluid in total, which would bring your numbers to 20% new stuff. I'm not sure which value is correct as I don't have an official spec on it.
2) Since you say that the pan was cleaned, but didn't mention about the filter. Does your model have a metal mesh type filter? It seems some models have a mesh filter which can be cleaned, and some have a paper filter which needs to be replaced. In anycase, I would think that cleaning/replacing the filter would eventually be necessary.
3) Just curious, what problems are you seeing now?

[jc]

Toyota recommends just a drain and fill. The differential is fed he same way by the filler hole. The pan doesn't need to be dropped and cleaned, but if you see the residue/film that sits on the pan, it's good maintenance. When I drop the pan I buy the strainer (aka filter) and new gasket. It only costs around $20 for this part. Then I clean the pan and magnets. Last time I installed two extra rare earth magnets to add to the metal collecting ability.

You're maintenace is procedure is probably ok (IMO), but not ideal. You would probably get an extra quart of fluid by draining from the pan and differential.

Regards, JC.

[aks2000]

The owner's manual of Sienna of year 2000 mentions transmission fluid capacity (drain/fill) as up to 3.7 qt. Based on my Google search, it appears that most people get 3 qt out if they open the drain plug. I am getting 2.5 qt out through the suction method. As such, I am not that off and I am also compensating for this by changing fluid more often. The color of the fluid always remains pinkish (and not brownish) since I started following this procedure.

My transmission shifts perfectly well with no issues at this time. I am just concerned that am I inviting some problem in future by not dropping the pan ?

My bigger concern is differential. My assumption is that differential fluid (.8 qt as mentioned in the owner's manual) should be getting refreshed by means of circulation/diffusion with new fluid added to transmission and as such, draining the differential shouldn't be necessary. But I really request experts here to comment on this assumption of mine.

I am not comfortable opening the differential drain plug (or for that matter the transmission drain plug too) and hence, may need to get this done at auto shop if my assumption above is not correct.

[wiswind]

The in-pan filter on my 2003 Sienna is just a nylon screen, so I would not expect it to clog up.
The drain and fill WILL mix and refresh the fluid in the differential in your 1st Gen (1998-2003) Sienna.
I'm not up on the newer than 2003, so I will not make comment there.

I am NOT an expert....but I did my own little test when I changed the fluid in my 2003.......I drained the pan & differential......removed the pan and cleaned the magnets and replaced the in-pan filter (which is how I know it just has a nylon screen in it).
Then I put the pan back on.....and put the plug in the pan but NOT the differential.
THEN.....I poured new ATF in through the dipstick tube SLOWLY and kept looking under the vehicle and after a quart or so.....YES, fresh ATF was running out the drain plug in the differential.
Then I put the plug in the differential and filled the system up.
This little test verified that the differential does share the fluid with the transmission....and changing as you are doing is also refreshing the fluid in the differential, as it is in the rest of the system.

The system of sucking fluid out through the dipstick tube and replacing with new ATF sounds like it is working very well for you.

A shop may do a fluid EXCHANGE (often called a flush) through the transmission cooler line.
They use a machine that collects the old fluid as it is pumped out of your transmission by the pump in your transmission.....and replaces that old fluid with new fluid at the same rate as the old fluid is being pumped out.
THIS service is also a good thing.
My only issue with a shop is that I like to use a more expensive fluid that they most likely will use.....but one can take their own choice of fluid in and have them use that.

[tmacm0nk3y]

I drive a 03 sienna with 60,000 miles on her.

You SHOULD drop the pan to clean the magnets that sits inside the tranny pan and you SHOULD always change the tranny oil filter.

if u want 99% clean oil, you only need to do a few more steps.
1.) drain tranny fluid from the drain bolt.
2.) unbolt and take out oil pan + clean the 3 magnets + change the transmission oil filter.
3.) place the clean magnets back onto the pan and bolt the pan in place.
4.) add ATF fluid till full.
5.)this is the fun part. follow what this guy does and you will get 99% clean fluid

[pjksr02]

I'll add that when I drain and refill, which is all I have done in 175,000 miles, I first open my differential drain plug. Most of my ATF drains through this hole, before I even open my transmission drain. I also have my engine idling while fluid is draining, until fluid no longer flows.

Many members here also drain using the transmission-cooler lines to the radiator.

See also: http://www.popularmechanics.com/cars...enance/1272521