I've run SOPUS oils exclusively in both of my vehicles since the first oil change, QSUD, PP, and PU. If I get a deal on Pennzoil synthetic, I'll go with it, but all things considered I'd just as soon have QSUD as either of it's cousins. It's good stuff, but don't tell anyone, Shell will probably raise the price. There's eleven quarts in the garage right now ready for my next two oil changes.