i talked to some mechanics about mine and they said to use yamalube 10w-40. some of them say to fill it untill the window is half air and half oil but some say to fill it 3/4 oil and 1/4 air. there is a number on the side of you bike close to the oil fill and on mine it says 1300 cm3. on the oil bottle it says 946ml witch is the same as cc so on mine i use 1300ml of oil thats like a qt and a half. if you have any q?s email me at montanacowboy20@yahoo.com