my 03 has 52000 mi. I do all the vlv. adj. myself. the way the gasket is designed, it will leak about 25-30,000 mi. The rubber gets hard and doesnt seal. The best way to fix is replace the gasket, spark plug hole gaskets, and the washers around the bolt holes. When I do my valves, I remove the radiator, this will give you lots of room. one very important thing to look for while your in there. Locate the engine mount on the front of the head. The bolts going into the head vibrate loose, then fall out. Now the engine is hanging from the rear and the frame will crack in the air box. Remove the bolts, lock tight and torque.