Yeah a member on this site had trouble on his power boat with his built big blocks. Seems that all the new on road oils lack enough zinc to prevent wear on the cams of high performance racing engines. So he wiped out like three sets of cams before figuring it out and switching to strictly off road use only racing oil. But you can't really use a racing oil in a street car, you will ruin the cat's and they are not ment to last that long.
So if you are running a pretty wicked cam in your Chevy or Ford based engine with some agressive springs don't use street oil.
As for MB
AFAIK the latest Mobil 1 5w40 that they use from the factory meets all there latest and greatest specs.