it uses a hypoid 80w90 gear oil. Go to your local motorcycle shop and pick up a bottle. I think you put in 5 or 6 oz of gear lube. But ask when you go to the shop. Make sure that the bottle says HYPOID 80w90 gear oil. If you use just 80w90 gear oil without the hypoid it will screw the rearend up. So make sure it sasy hypoid