I guess it's all about the additives in the oil. I thought the same thing...oil is oil. Well in no time my clutch was slipping like a mofo and I thought it was fried!! I found an Amsoil dealer local and the ****** is perfect now. It was amazing how easily it shifts now and neutral is no longer a problem to find, get it 1st crack always
Unless the valvoline bottle has a picture of an ATV on it you're running car oil, Valvoline makes a motor oil specifically for 4 stroke atv's, which is what I use because it cost's about a third of what amsoil costs. Amsoil is like 8.99 a quart at the cheapest local shop, vs 3.19 a quart for valvoline at auto zone. Definitely stay away from motor oil designed for cars though, the friction modifiers in it aren't designed for a wet clutch and will make it slip like a greased fat kid on a wet marble floor