I'd really like to know, because I'm paying nearly $6 a qt for what I believe is true PAO based synthetic. I use the 5w-30 in my car and the 15w-50 in my bike. My feeling is that if Mobil One has changed over to a Group III oil, then I'll stop buying it, and look for a less expensive oil. I don't mind paying extra for Mobil One if it is indeed a PAO based oil, but if it isn't then I don't see why I should continue to pay extra for it. Can anyone provide a definitive answer on what Mobil One uses for base stock, PAO or group III?