I know is sounds bad, but I use whats on sale, as long as it does have the friction reducers.
I usually just buy it buy the case. Can't say I have any problems, I even broke in the engine on Quaker State!!!!!
I think if it meets the specifications, it is fine. Compared to cars or trucks, the atv's only go a few miles between changes most of the time. I'm sure the racers disagree, but for trail riding, just keep the filter clean and the wheeler will last many years.
Lexx w/ FMF Powerbomb head pipe
Longhorn Clutch lever w/reverse