I don't know myself .Amsoil in general at least in my opinion has a lot of hype and hoopla behind it . There may be something to it or not .
Bar oil in general speakng is nothing more than machine tool way oil .In other words oil with a a tacking agent in it ( STP ) ,kind of like smelly gear oil without the smell .You buy something like Mobile Vacta which is Mil spec way oil you pay through the nose for it .
Although nobody fesses up about it I do believe that "winter " grade bar oil is just a thiner weight oil with a tacking agent .