I changed my front diff fluid in my 05 BF 650 and the fluild was brown, not milky like it had water mixed with it. So I put fresh oil, Mobil 1 10W-40, in it, ran it around came back and changed it again thinking I would flush it out and the fluid came our just as brown as before in just a short ride. Is this normal? What is causing the fluid to turn color so quickly?

 

I called my dealer and he said that as long as the fluild wasn't milky like it had water in it don't worry about it. He couldn't explain why the fluild was brown though, seems like there must be some explination, must have something to do with the metal or coating that is on the gears and other moving parts in the housing.

 

Is that the recommended Oil for your differential? Thought they all used 80W gear oil.

 

No, motor oil is the right stuff, the only difference is the dealer said he uses conventional oil. The oil is the same color as whatever material the gears are made, or maybe it's a coating that the gears are plated with. This is what I could see looking through the drain plug. As he told me as long as it wasn't milky or had metal in it not to worry.