well I've been using yamalube in my Big Bear because the dealer said that if you use regular engine oil your going to have serious trans. problems due to the oil working in both the motor and trans.......plus I'd rather be on the safe side and spend a lil extra then be trying to pay for a new trans. because they wont warranty it becuz u didnt use the rigt oil...so i would definitely recmend yamalube

 

Valvoline has a new atv oil out. They sell it at autozone for about $3 a quart. I've been using it for a while and it doesn't break down as fast as yamalube.