neunfünfeins

I don't want to turn this into yet another religious oil debate, so I won't ask "why not?"

I'll simply add that I'm specifically using only the 15w50 grade of Mobil1 (not all Mobil1 is created equal) after doing my homework & comparisons. I concluded that it was suitable enough for me with my mostly stock/street non-tracked application, but it's not for everyone (no substitute for doing your own research). The rebate is just icing on the cake.