Been in the bike for about 6,000 miles now. According to
this Amsoil produced test, it's petroleum. I've used the Triumph Mobil, regualr Mobil MX4T, Amsoil, Mobil 1 Gold Cap, and now Valvoline, and I haven't noticed any difference between any of them...the bike runs the same, and the clutch has never hiccuped in almost 42,000 miles.
