I have a 99 yz400f and no service manual. I know they're only 30 bucks but I'm a cheap little monkey. I change the oil every 3 or 4 rides but when I fill it back up it only takes 8 oz plus or minus (200 ml). I own a couple of Grizzly quads (excuse my language) for work and they take 2 quarts! It just doesn't seem like enough oil. Please advise.