I DON'T GET IT
Rotella T Synthetic is API SL approved. This would indicate it can be used in all gasoline engines (that require/allow the 5W/40 viscosity).
Mobil 1 Tri-Synthetic is no more a 'true synthetic' than Rotella T based on what I've read. Don't get me wrong, I've trusted M1 for many years, but the Rotella T Synthetic sale price was too good to pass up.
API SL is API SL. What am I missing?
84 733i 5-speed - M1 or whatever is laying around
89 300TE 183,xxx - M1 since 60K miles
01 VW Eurovan GLS - Rotella T Synthetic, 5W40 is all they allow