AnalogMan wrote on 03/11/15 at 03:43:42:


Oil from an air cooled engine with a wet clutch will always look "bad". Doesn't mean anything really. Bad is when there's metal chunks in the oil. The only way to know is to have an oil analysis performed. Personally, I wouldn't bother on an engine that can be replaced at the cost of a used bike.

The clutch particles really make it black. On my 2T dirt bikes the transmission fluid turns from red to gray in about 2 hours of use and gets changed at 5 hours. On the 4T dirt bikes (water cooled, wet clutch) the oil gets changed every 5 hours and I usually DO find metal in the filter. And I've never blown an engine.