You should have provided pictures of the rust areas. I can't attempt any solutions without a view, if structure is single point critical juncture.

 

I feel bad for anyone who's vehicle is toast because of rust, but if you live in an area where winter roads are salted you either live with a rotten car or rustproof.

 

Our 2005 is showing Damaging RUST

Only solution is to drive a sacrificial beater during those months. Buy one or wait for rust to turn your car into a beater. Don't trade it in for $300. Use it to save your next car from rust.

 

Sorry circus but I have to disagree with you. Rustproofing works, simple as that. And either in DIY applications or retail locations, many have been around for over 40 years. There's no need to drive a car and just watch it rot away over the years.

 

Sorry circus but I have to disagree with you. Rustproofing works

Beware of the "rubberized" or tar base undercoatings. Does more harm than good. 1st hand experience.
Wax or oily helps but require reapplications.
South Main: rustproofing

 

Agreed, a rubberized undercoating is not good and its also not the same as a proper rust inhibitor.
Rust is basically a chemical reaction, so you need to stop that reaction from happening, thats what actual rust inhibitors do. Rubber just traps moisture and allows that reaction to accelerate.
Not trying to be a dick by saying this, I just dont understand how people that live in the salt belt are shocked when their car eventually rots out from underneath them.
Its like changing your oil. Its a preventative maintenance item that has serious consequences if you dont do it.
And no, not everyone needs to do it. If I bought a new car every 5 years and traded in, I probably wouldnt waste my money. But I keep my cars for about 10 years, I do live in the salt belt, and I like the idea of getting more money for my used vehicles because I can say they are rust free.

 

Agreed, a rubberized undercoating is not good and its also not the same as a proper rust inhibitor.
Rust is basically a chemical reaction, so you need to stop that reaction from happening, thats what actual rust inhibitors do. Rubber just traps moisture and allows that reaction to accelerate.
Not trying to be a dick by saying this, I just dont understand how people that live in the salt belt are shocked when their car eventually rots out from underneath them.
Its like changing your oil. Its a preventative maintenance item that has serious consequences if you dont do it.
And no, not everyone needs to do it. If I bought a new car every 5 years and traded in, I probably wouldnt waste my money. But I keep my cars for about 10 years, I do live in the salt belt, and I like the idea of getting more money for my used vehicles because I can say they are rust free.

Occasionally bathing the areas splashed by salt/road muck never hurt either... (it's that maintenance thing!)

 

Lately the price of used rust buckets are high. Too many idiot buyers. Patches (my winter beater) can't last forever.

 

When I lived in salt winter country, I had my new car oil sprayed. Yes I know some folks think that is terrible for the environment as initially some oil will drip off. But the rest gets soaked into the rust already present and the metal.
There is a reason the Chinese ship stuff across the ocean with oil on it.
I think it is environmentally the best choice as it keeps a car out of the junk yard for a few extra years. Adding up that is 1 car out of the junk yard vs maybe a gallon of oil spread out over a million miles (the lifetime of cars that drip).

Anyhow, that car lasted many years (over 10) without any rust other than some surface through the paint from the outside. Frame and wheel wells were perfect.

I had it sprayed once, and that's it.

This treatment was in the past recommended by Consumer report, they even had their own formula for mixing the oil to make it better than plain 30W oil (was a mix of light and heavy oils added).

 

Yes I know some folks think that is terrible for the environment as initially some oil will drip off.

Below is from Krown rustproofing. I suspect most would be the same though, that they are not actually environmentally bad.
Used motor oil on the other hand is apparently really bad for the environment so not a good thing to spray on cars.

 

Back to the OP question... The only real option is probably major structural repair at a body shop. That said, if you know a talented welder, you can almost always weld reinforcement plates in place to strengthen rust fatigued metal.

 

Could easily solve the jack up area's, course issue is the rust is probably just as bad all over, so will the wheels fall off, or a person's feet go through the floor someday soon ?

 

Years ago I was talking to a friend. We were outside and I commented on his truck and how rust free it was compared to my F150 that was completely destroyed with rust.
Long story short, his truck was rust proofed every year, mine was not. He said he used Krown.
No, I dont work for them, I have zero affiliation, I just know that from that conversation I was sold on rustproofing.
There's a Krown place not far from me so thats where I go. I like to DIY stuff but I'm not crawling on my back getting caked in a bunch of oil for a job like this.
Just because I go there no, I would not drink it either. But I can say from personal experience it does not eat holes in your driveway like motor oil or tranny fluid etc. Once its done dripping it leaves a big ring stain on the street or driveway that is not permanent.

Not sure how someone can say idea of rust proofing is amusing. It works. Say whatever you want, but from personal experience I know it does.

DIY with some POR 15 or the like, , take it to Krown or Ziebart, whatever floats your boat, but you dont need to stand there and watch it rust, there are options.

Back to the OP- It sucks that the body is so rusted. I would think the only way to fix that is as Bill stated, major structural body work, and at a cost thats probably higher than the value of the vehicle.

 

Not sure how someone can say idea of rust proofing is amusing. It works. Say whatever you want, but from personal experience I know it does.

The point was that, 4-5 coats of waterproof, physical barrier (paint) didn't stop the rust, so it's amusing to think that a very thin coat of a very light oil would stop it. Don't get me wrong... I 100% acknowledge that rust proofing can make a car last longer and certainly be more maintainable when it comes to underneath parts. I just don't see how it would help the highly rust-prone body areas like rocker panels or, on other cars, wheel well corners. As an aside, my van is definitely in the worst-case-scenario environment. The ground is salty. The air is salty. The water is salty. The roads are treated with salt and sand and the bridges are treated with liquid salt. If you've ever seen a salt spray tester, it's a sealed box that fogs an item with a salt spray. My home is basically an open life-sized version of that.

 

Apologies Bill. My misunderstanding.
Where I go the guy was pretty good at explaining things. So if I get any of this wrong you'll have to excuse me.

Salt is an electrolyte and rust requires a trifecta to form.
You need the salt, the electrolyte, the steel of course, but you also need warm moist air. Warmth accelerates the molecules and the moisture allows them to spread.
So you can drive around all winter long and your black car could be pure white from being caked in road salt, but its really not doing much damage.
Come summer time you have that trifecta and thats when most of the rusting (oxidation) happens.
Rockers rust out because warmth from the passenger cabin meets cold air from outside. That equals condensation right inside the rockers.
Same idea in the summer but colder air inside meets warmer air outside.
Wheel wells because moisture is trapped there as well.

True rust inhibitors actually have chemical compounds that neutralize the effects of the oxidation. Oil types creep into those hard to reach areas just like moisture does.

Again, I'm just regurgitating how it was explained to me so I may have gotten some of it wrong, but it makes sense most of what the guy told me. Especially about the moisture and warmer air.

 

You know... I always curse rust but really it's been good to me. Knowing a little body work helps.
In 1980 I bought a 1976 one ton pickup for $250. How? Rust. Still have it. Has a full frame.
In 1985 I bought a Triumph Spitfire for $200. How? Rust. Still have it. Has a full frame.
Etc.
Therbi, springtime doesn't cause rust, puddles quickly rinse off any salt. On the other hand, a heated garage is kriptonite. As for rockers, they catch hell from the tires and any multi layered, thin as paper, boxed in area eventually fills with mud and gunk.

 

As for rockers, they catch hell from the tires and any multi layered, thin as paper, boxed in area eventually fills with mud and gunk.

Not to mention, scrapes and scuffs from wives driving over high curbing and roadside debris by cutting corners too sharply. I don't know what it is... My wife is an exceptional driver EXCEPT for making right turns in the Sienna.

 

My 2006 Sienna succumbed to rust at the rear Jack points in front of the rear wheel. At that point it had 180,000 miles and was ready for a trade.

 

I wonder if it's accelerated by the use of jacks which would rub/scratch/gouge to expose metal. Or is it simply that then entire frame is weak and if it was jacked anywhere else (not that you can do that anyways) that it would give way to the pressure/weight.

 

Want to add thesr photos or rust at right rear jack point
Hope this helps someone. Have seen other siennas with
rust in this area

 

rust at right rear jack point

Have repaired such rust in the past but gave it up 30 years ago. In one respect it's dirty nasty work, sandblasting, cutting and welding. On the other hand it doesn't take much time and doesn't have to look perfect. Your going to have a hard time convincing a bodyshop to fix it. How deep should the repair go? Latter blamed for rust elsewhere. Lousy pay.
If I had to pay someone, I would live with it, jack it up somewhere else.
As for myself, I know how to fix it, that's different. That's how I buy them. Cheap.