By getting the full synthetic you can go a full 100 hr.'s between oil changes. Engine runs better and uses less fuel. I am sure Amsoil can explain their oil much better then I can. You can go to Wally's world and you can buy your oil for less then 2 dollars a quart. Good oil, I use it in my camp mowers. Yes you get what you pay for. Look at the different between a Weed eater one rider and a Ferris ZT, you can see the different. Rub the 2 dollar Wally's oil between your fingers and then the 12.00 dollar Amsoil and you will feel the different.