quote:Chevron Supreme Motor Oils SAE 5W-20, 5W-30, 10W-30, 10W-40, and 20W-50 are formulated with ISOSYN ® base stocks, a shear-stable viscosity index improver, and contain detergent, dispersant, wear control, antioxidant, corrosion inhibitor, and foam suppressant additives.
I knew from the Chevron site that it was based on group II, but I was wondering what IsoSyn was. Maybe an additive package or a dose of group III mixed in?
Yep, you're right. A quick search shows that this topic has been discussed many times and the conclusion was that it was a Group II+ oil.
See this thread for example.