(Oops, goofed and did this reply as an original post, sorry for the confusion as a result.) Anyway, perhaps you all are right in your respone to fhmajid, however when I purchased new rotors for my '92 300TE from the MB dealer a couple of months ago, I was told specifically by them, unsolicited, to be sure I removed the grey coating before I used the rotors or what I said in my earlier post would result. If I were you, I'd call or visit your local MB parts department and ask them, to be absolutely sure. Maybe my guy was wrong, (thus I am too), but I don't know why he would've said that if it wasn't necessary.