Rust on W124 brakes
 

Had my car in the shop this week for an oil change and asked the mechanic to check on a brake noise. He ended up replacing all four brake rotors and the pads. He said all the rotor surfaces were rusted, but particularly the rears, to the point that they would not perform adequately if called upon for emergency braking. (I had had no braking problems other than the squeal I reported to him.) What bothers me is that the rotors had lasted so little time. The rears were new only 18 months and about 9000 miles ago. The fronts had been replaced 3 years ago (about 24,000 miles ago). I live in Massachusetts where we can get snow and the roads get salted, the car is outdoors at all times, my commute is only about one mile each way so the car does not get thoroughly warmed up most days, and most days I do not do heavy braking. My mechanic argues that the brakes are rusting rather than wearing out and that more frequent use might actually prolong their lives.
Does this sound reasonable? Do other Northeast owners using MBs as daily drivers find their brake rotors rusting so fast? Of course, I also wonder if my mechanic is being overly cautious (or dare I say it, overly greedy?).

David, the rotors on our 124 cars develop a light rust film while washing the car. It's difficult to tell how thick the rust might have been on your rotors, but in the future if you see rust developing take your car out and do some hard braking to remove the rust coating. If your car sits outside all the time the rotors are more susceptible to rust.

The rotors are cast iron, so they'll rust pretty easily. Usually just a light film develops, and that is easily worn off with regular use. If your car sits a lot in rust-prone conditions, the rust could get bad enough that it would interfere with braking, but I would think that you'd get some symptoms (noise, weak braking) before that would happen.

Or playing you for a fool. Rotors rust, as pointed out in previous posts. 24,000 miles can vary wildly in terms of brake wear. Does seem like the rears are prematurely wearing out. If he is telling you the truth. They can be measured. Makes me wonder whether they were truly below minimum.

Steve