Anyone know how Tesla bodies are treated with anti-rust at the factory?

That's a nearly universal practice.

I don't know what Tesla does, but I'd be pretty surprised if they weren't doing this or a new update to this process.

 

I worked at Toyota in the Paint Department. We received the raw metal body from Body Weld.

It is a complicated and refined process to seal and rustproof the body. It is a science unto itself.

Briefly to describe it the body is washed with degreasers and hot water - then it goes through a Phosphate Dip that coats the entire body with a Phosphate coating - it is then washed and goes through a Electro Deposition Tank where it receives an entire Ecoat (Electro Deposition Coating ).

When going through these dips the body is completely submerged and in the case of the Ecoat the Ecoat paint is positively charged and the body is negatively charged so the coating gets into every nook and cranny of the body.

Once cured in the oven the body then goes to sealer, PVC and Anti -chip where different sealants are applied to the seams, underbody and wheel wheels as well as the rockers.

That is a very quick cursory explanation

Most automakers use this process for sheet metal bodies

Most Automakers have a proprietary way they do things and don't share a lot about their paint processes

Analyzing the automotive painting process in the factory | Equipos Lagos.

 

Toyota didn’t seem to do much with their suspension frame members. And bolts. Off topic though.

 

At our Toyota Plant and all I had visited the frame members are coated in the Phosphate Electrodeposition process on a small parts line. Bolts and fasteners on the under carriage must meet certain rust resistant specifications.

All manufacturers are now coping with the effects of the aggressive brine coating that municipalities put on their road surfaces. These coatings are so aggressive they attack car parts that used to be unheard of as far a rust - actually eating brake lines and brake components up.

Worse than salt, brine sprayed on roads will munch your car to pieces - The Washington Post

Wisconsin Communities Search For Road Salt Alternatives | Wisconsin Public Radio
"Salt that we see on the roads in the winter, doesn’t just disappear," said Amy Barrilleaux, spokesperson for the Madison Water Utility and a member of Wisconsin Salt Wise, a Dane County-based advocacy group. "All that salt we’ve been putting down since the 1950s in Wisconsin is with us. So anything we can do to take a step toward getting control of that, is really important."

Cities Are Cutting the Salt from their Winter Road Diets – Next City

Environmental groups mount campaign against use of brine as deicer in New York - Fingerlakes1.com

Reality Check: What Road Salt Is Really Doing to Your Car
"Your car’s undercarriage is where road salt and other corrosive chemicals are slowly eating away crucial mechanisms. Chemicals that are easily washed off your car’s exterior tend to become embedded in your shock absorbers, settle on your wheel wells, invade door panels and rest in secret cavities and crevices you can only observe by placing your car on a lift.

Even worse, these chemicals are hygroscopic, meaning they attract and retain moisture. When they stow away in your undercarriage, they act as moisture magnets that slowly corrode any metal surfaces. If this is left untreated, you may face hundreds, if not thousands, of dollars in damages in coming years."

Sorry for running on, fascinating topic to me.

 

Thus, there is still a need for aftermarket rustproofing, if correctly applied. The caveat is that it needs to be "correctly applied."

The military and certain commercial users do it right.

Commercially sold aftermarket rustproofing has a bad reputation as it was poorly done and for appearance on;y and sold with a near worthless guarantee.

 

You might be upset by the idea of sliding off the road in the winter, but you can be hurt (or worse) in a corrosion-compromised car all year round.

 

If that brine is fossil fuel well waste water, it is also hot in a radioactive sense.

 

And the Caveat to your caveat is:
It is almost impossible for the average car owner to find out what qualifies as "correctly applied".......and then whether or not a specific shop DOES that.
So the bottom line is: In most cases, it is still a total waste of money and will sometimes make matters worse.

If you live in an area that salts the roads in winter, it is probably a more effective use of your time and money to get an "underbody wash" periodically during the winter season.

 

Method that works for me with our 2010:

1. Deal with one end or the other; either will take a full afternoon.

2. Raise and safely support the chosen end.

3. Remove the wheels.

4. Remove any plastic panels obscuring the suspension components. Which to remove is a judgment call, some are superfluous, some are worthwhile. Any screws or bolts are oiled while out.

5. Brush/blow off any loose dirt/grime, then brush on undiluted boiled linseed oil.

I do this to every suspension component I can reach, a couple of times now, over 10+ years, holds up pretty good.

 

Been there, done that - had TWO cars (Ford Mustangs) lose brakes on me in city traffic due to rusted-through brake lines. Luckily, enough of the brake system was intact to stop the car with nothing more than one freaked-out driver (Moi).

Road salt - even before brine - in Chicago is a car-killer. I never had a car make it to 100,000 miles. They just got to the point where you couldn't repair them anymore.

Rescued a '96 Pontiac that was my mother's. Brake lines all replaced. Brought it to Texas - replaced brakes all the way around - everything. Calipers, linings, rotors.

As John says above - "hygroscopic". Car continued to rust away even in Texas! Chunks kept falling off the underbody. Only 79,000 miles. Sold it for $500 to a guy who could put the still-great engine and trans into a Texas body.

I have a 2000 Ranger with 344,000 miles on it. Texas vehicle. Being used to Chicago cars, I hate working under the vehicle. With the Ranger - bolts come off like they were put on yesterday.

'Course, if it snows here - you stay home..... (no plows, no salt)

 

It's not as difficult as you say.

Simple enough, you can simply remove the plastic under body panels and spray any and all metal to metal and plastic to metal gaps with a cheap penetrating oil compound like Liquid Wrench like this found at Walmart.

LIQUID WRENCH Penetranting Oil, 11 oz, Aerosol Can - Walmart.com - Walmart.com

That includes the brake line nuts and all bolts. Get the bottom seams of the fender wells, doors and quarter panels ans well as the bottom lower seam of the hood and the hatch. Those are the places where moisture settles with salt and debris to cause rust.

A week or two later, after the solvents of the Liquid Wrench has evaporated, spray the same areas with a rustproofing compound like this.

This simple procedure will add years to the life of your car. I would also coat the brake lines with rustproofing.

Rusting doesn't begin with the panels, themselves. It begins with the crevices that trap moisture, debris and salt.