Icalled Mobil 1 at 1800-ask-mobil, and asked them how their synthetic 15w50 would work in a ATV. they said it would work fine in a 4-stoke, wet clutch. they said it had less then 1% molybdenum in it. It still worries me about clutch slippige. i read that oil article at www.yft.org/tex_vfr/tech/oil.htm it was a great article with lots of info on motorcycles and oil. thanks to whoever posted the info on how to get to it.

 

Ive got the 15w50 in my ATC 350X . I dont remember though if its Castrol or Mobile . But it is the full synthetic . I dont have any complaints at all. It starts excellently all year round . In the winter I do let it warm about 3-5 minutes before takeing off or I do get a slight squel when I first engage the clutch .

 

STILL AFRAID TO TRY IT, DUE TO CLUTCH SLIPPIGE. MAYBE I WILL GET UP THE NERVE SOON.

 

I have been using it now for about the last 50 hours of riding. I have never had clutch slipping. Many other people are successfully using this oil as well.