OK, I have read a bunch of posts that knock Valvoline oils, from All Climate having no moly and weak additives, to Super Syn being a Group III+. What I want to know is what is the actual difference between Valvoline and others such as Castrol, Pennzoil, etc? I remember when I was younger than no one would use QS in this area because it was supposedly prone to gunk up motors. Now Pennz and QS are two of the supposedly better oils. Just trying to stay on the curve so to speak.