Orijinal gönderinin sahibi: oldturkey03 ,
Anytime you have an oily spark plug face, check your valves. Do a compression test as well as a leak down test. The knocking you are hearing, could easily be your valvetrain, camshaft, or your rod bearings. Especially since all this started before your OBD showed a 0303. For now, I also recommend that you drive as little as possible to avoid any further damage to your engine.