I'm actually going to run the new Mobil 1 "extended formula" in my Crossfire. Now its thicker (15w50) but I don't see a problem with running it, after all, in the past I've run thicker grades w/o a problem. Case in point, my used 87' Grand National that I bought in 95' w/ 87K on the clock, I ran 20w50 Mobil 1 in that and it called for 1ow30, so I don't see a problem. Anyone have a problem with running heavier oil in the Crossfire?