Surface rust (thin powdery layer) is not a problem. It gets buffed off within the first few brake applications of the day. But as you note more aggressive rust can be, if it causes pitting in the braking surface or if the particles become large enough to cause accelerated wear. The degree of problem is dependent on how long the car sits unused in rusting conditions and of course salt is a tremendous accelerant. It's been many years since I lived in the Rust Belt, but the horrors of salt corrosion are still etched in my memory.kaiat wrote: ↑Mon Nov 16, 2020 3:44 am...The roads are being salted during the winter months and this has the nasty effect of causing cars to rust badly. Brakes are easily corroded and seize up under such circumstances. The rear brakes are particular affected since they apply less force than front brakes when braking. ...
+1knightmb wrote: ↑Fri Mar 19, 2021 8:41 pmI can't speak to everyone's experience here in regards to salt and rust wearing out the brakes, but I can say that I have friends and family who get told the same thing, that the brakes need replacement by every dealership. I have them take it somewhere else for a second opinion and so far 100% of the time, the brakes are actually fine. I never touched my brakes before trading in my 2013 with 75K miles on it and the brakes were still in excellent condition, despite all the constant stop and go driving I did for 8 years.
Of course, that doesn't mean someone else won't have brake issues if the environment is literally eating the brakes, but I would recommend at-least getting a "non-dealership" second opinion.