I have an '06 TE610 and have done two oil changes on the bike since I bought it. Both times it has only taken a couple days (of street riding) before the oil in the sight glass was black again. Does anyone know if this is normal? How often do you change the oil in your thumpers? I'm used to changing the oil in my street bike whenever it starts to look too dark. Would prefer not to be changing my oil twice a week. When I did the first change the old oil that came out had a lot of sediment in it, so I figured some of that may have still been left over which turned the first batch of fresh oil black. Figured the second batch would last longer, though.