true story: I ran Mobil1 in my old 85 S-10 Blazer for a month, DRAINED it, and ran 75 mi down the NJ Garden State Parkway and back at high speed. the POS didn't even run warm. 
I did it becuase I wanted to swap out the Iron Duke for a 305, and I never believed the propganda about running the motor with no oil. now all I ever sue is Mobil 1 in all my vehicles