I use synthetic oil (which I'm not going to identify so as not to resurrect that dead horse) which I change about every 3000 - 4000 miles. I checked it before changing it this time,and it was fairly clear. Just for sh*ts & giggles, added Seafoam to the oil, and drove the bike about 35 minutes, and then carefully opened the drain plug. Could not believe the difference in color that came out - totally black, as if I had used dino oil for 20,000 miles. And yes - SF is a petroleum product.