well, I can tell you one thing. The oil REALLY is the lifeblood in this engine. While you might get away with abusing the engine (via dirty oil) in other engines, I would be hesitant here. The Cams and Crank are both seated directly in aluminun, no bearing races or journals. Which means if you do have a less than satisfactory filter, if it is letting dirty oil back into the engine, your engine may fail prematurely. This means replacing either the entire head (since the bearing journals are machined directly into the head) or the lower end, or perhaps both!!!! I'll spend the extra money on a K&N...
