Originally Posted by maxcichon

I've done a few of these on our cars, and more than a few on old US V8's.

I've yet to see an oil leak from the OEM Mercedes valve cover gaskets. The BUNA/aluminum seal seems to work perfectly, unlike the old sheet-steel VC's of my youth.

I apply a very light coat of silicone vacuum grease (viscosity-stable to 212F) to the gaskets, just because it's the way I do it.

The RTV you add, IMHO, does nothing. The Germans got this one right.

The RTV they use, or the application of it, is a real issue. More leak, with time, than don't.
But I've had great luck (?) using my method of true-cleaning and proper application of "Black" Permatex.

And, that's MY 2 cents.

The value of advice, in general, is inversely proportional to it's cost.

Chew on THAT one, folks!