Little by little we are moving to the 0w-20 oils. Other then Redline's, most 20wt. oils have lower HT/HS numbers. Ford Mustang's call for a 20wt. oil. Wouldn't you think using a 20wt. oil with a HT/HS number of around 2.8 would be to low for this type of car? I don't think we have any UOA of such a case but it seems like it would be. Or what about the new Ford pickups calling for 20wts.? I think I'm asking a question we just don't know yet.