Rust through warranties haven't changed much in decades. Basically they typically state something on the order of ten years/ 100,000 miles, and they are referring to rust that was caused by a defect in the metal that has been missed during assembly, and simply painted over. There never has been a warranty for damage to the vehicle caused by exterior damage that results in corrosion.

What's sad to me is if it wasn't for rust, I could keep vehicles basically forever, and do the same for my customers. But ultimately corrosion is the determining factor when it comes time to call it quits on a car. Everything else I can fix for less than it costs to replace the car.

BTW, you won't see this problem with domestic trucks until they are two to three times older than your Toyota was. The thickness of the steel being used is part of the reason, and the open channel frames also allow the salt to not be trapped inside the frame where it gets to work at the metal. The box frames in the imports allowed for good strength, with less metal. In a salt free world, that is a win for them and the consumer. The box frame is lighter, which is a material and fuel savings. Plus the box frame is actually cheaper to manufacture. In reality though, the traditional "C" channel with a heavier gage steel will simply outlast the lighter box when exposed to the same corrosive conditions. I mentioned in another thread on this subject, my 94 Ranger has no such corrosion issues with the frame, but it is losing the spring shackles in the rear. The spring shackles would be the same gage steel as the Toyota frame. I can replace the shackles in a couple hours. It takes two to three days to replace a frame, but it is possible to do.

Thanks much for the interesting information. It doesn't quite explain the variances in trucks (old Toyota no rust, Ford 150 same age and locale rusted through) Instead of recalling vehicles Toyota would have been better served by going back to the drawing board with new specs.

John_g gave interesting facts on frame construction. Here's another way-out connection on truck frame hole-through.

Before I retired and when A. O. Smith was yet making frames for Ford trucks (in Milwaukee), they encounter an environmental problem. It was seagulls from nearby Lake Michigan! (I worked about 1.5 blocks from this location.)

The truck frames were welded together and the first primer applied by dipping, and then temporarily stored in large stacks outside. There would be at times thousands of frames, principally for the Ranger, stacked in the outside lot. The gulls liked to congregate in the air above these frames and crapped a lot. The topmost frames received the most poop bombs, but frames deeper in the stack were affected also depending on the wind.

There were no little elves on the final production line to clean inspect and clean these frames. These frames, poop and all, continued through the finishing process which were dip and spray tanks including painting. The frames tended to hole out where the poop bombs had been. Those destructive bombs are acidic and could affect frames with the final paint as well.

One solution that was tried was carbide cannons to scare away the birds.. As I drove past this lot going in to work, there would be load bangs at random locations in A. O. Smith's lot. Of course, this noise did not set well with a residential neighborhood that surrounded the plant. A. O. Smith did try to be a good neighbor and limit the time of the barage, but of course, the barage had to being soon after daylight, and there were 2nd and 3rd shift workers in the neighborhood who were trying to sleep. It was contentious solution.

It was found that the gulls avoided perigine falcons and other birds of prey. (The piegon problem in downtown Milwaukee was eliminated by using falcons.)

The final solution was A. O. Smith exiting the truck frame buiness. This business was sold to Tower Automotive and not long after that, frame making at this plant was consolidated with other facilites out of state and the Milwaukee plant shuttered.

You might say that frame manufacture at this plant was "for the birds".

Well my '79 Toyota P/U frame was rust proofed at the factory; my '95 Ford Lemonzine was not. The rust proofing was black stuff all over everything - maybe it was dipped? - and is now peeling off here-n-there.

Perhaps the newer Toyota's probly built here in the US of A do not get factory rust proofing anymore? ie maybe now it's a buyer's option.
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1967 in Buffalo NY a friend had about a '58 Ford. The left headlight burned out. He junked the car. There wasn't enough fender left. Couldn't even replace the fender. They were see-through fenders. At that time Buffalo put more salt on the streets than anyplace else on earth.