Just rebuilt the top end of my 400ex, and changed the oil before I started it back up (drained out oil reservoir and from the crankcase). The oil was black, and looked like somethin had been added to it, it wasnt the normal "used oil black". I put in 2 quarts of fresh oil, and after maybe 20 minutes of riding i went to check the oil, and its now its black and almost looks like it has some very small air bubbles on the dipstick. Doesnt look anything like I would expect it to. What could cause this to happen? Do additives like seafoam cause motor oil to change colors or go bad faster? Its my first oil change since I bought it, and I wouldnt be surpised if the guy I bought if off put something in it to hide the oil leak.