I am wondering why all the mini China quads use 15W-40 engine oil. Is it that it does not have the anti friction agents that are bad for the clutch? I was wondering why a person couldn't poor in 10W-30 or 10W-40 Yamalube. I don't want another different kind of oil sitting around my garage.

 

I use Valvoline 10w-40 in all of my Jetmoto and Honda thumpers. Almost 2 years and no problems with the Jetmoto and a couple of decades for my Honda thumpers. You will be fine using Yamalube 10w-40.