I'm curious if anyone knows. Does Stihl make their own oil or do they buy it from some major oil company and then rebrand it as their own. I'm not dissing Stihl as I use their Ultra at 40:1 in my engines once broken in. Perhaps they buy a base oil from a major supplier and then add whatever ingredients that they think is best.

I think I read somewhere that Stihl oil is produced by Castrol. I do know that just because you read it somewhere (especially on the internet) doesn't make it true.