Hey guys, I just picked up my 2001 400ex last week. And ever since, its been blowing some blue smoke. I think its burning oil. So i changed the oil and the oil filter, the oil was black. The original owner used 10W40 in it. I was told it may not smoke with 20W50 oil. So i tryed that instead. But its still blowing some smoke. Not as much as it was with the old 10W40 oil. Could it be the ring's? Or valves? Thanks, Ryan.