I have received numerous different recommendations as to what oil I should use. Have yet to get a consistent answer. Last oil change, about a year or so ago i went with the previous owners recommendation of castrol sae 10w40, no serious issues occured...But since then i've had alot of other opinions on the matter. Bike has 7700 miles on it, clutch makes some clanks here and there and sticks in neutral from time to time but has yet to slip on me.