Hi,
Installing new brake rotors on E500. Notice that they are coated in dull grey finish, that is no metal is exposed.
I tried to rub it off using mineral spirits type solvent. Didnt work. Do I actually need to remove the finish before installation? If so, do I need to remove from the entire rotor, ie hub mounting area etc? What should I use to remove it.
Is the grey substance an anticorrosion protectant ?
Thanks and regards
farrukh

1994 E500 53K miles - triple black
1995 E320T 60K miles, Starmark, E500 suspension upgrade