Maybe I am lucky, but I changed out the ORIGINAL rotors this year on my '87 300E. They went 150K and were approaching the thickness limit. I have always thought that if one replaces the pads before they hit metal, the rotors would wear naturally. I have never had a problem with brakes on my MB. In fact, I also have a '91 190E 2.6 with the original rotors at 138K
Anziani