Mobil flat out told me that Mobil 1 is a premium brand and Supersyn's position in the market is on a lesser tier, but they insisted it is great oil. I may be mistaken, but I think their warranty is better on the M1 product line, too.
It isn't only Exxon Mobil that rates them this way. FCA allowed MS6395 certification on Supersyn but not Mobil 1. Why? Because M1 competes with Sopus' premium product line (Pennzoil Platinum). MS6395 was the context of my call to them, to ask why M1 doesn't get the FCA approval. In short, they are in bed with Sopus. Politics. They clearly stated, though, that M1 was the higher performing oil line. I'm sure my Jeep, though, would have no complaints running Supersyn.