Elkbow

I have about 400 miles on my machine since the last change on the rearend and I checked the fluid today and it was discolored, but far from black. I could see some specs of silver in the fluid, but it wasn't bad. Maybe you should try the Amsoil 75-90 Severe Gear and see what it does for you, because the fluid shouldn't be black in a couple of rides. The Amsoil is like $7.20 a quart, which would last you for about six changes, its cheap insurance.