I dropped the coolant out of my 1997 yz250 and it was a blacky green colour. I dont think its oil because when i let the coolant settle in a bucket, there was no seperation of the oil and water. also it has sedements/ particals in the coolant i took out. I have had my waterpump seal replaced and recently had a top end rebuild, where i replaced the piston, rings, and all gaskets. Does anyone know what is causing the coolant to go this colour. I have ridden the bike about 3 hours since the rebuild. I dont think its blowing white smoke, pretty sure its normal blue, goes away when hot.