I just rode the rattlesnake enduro, a mud fest. I rode speedsville last year in the mud as well and in both ride the c/s seal leaked oil all over the chain. I cleaned the seal last year with a film negative and it was fine for a full year. I'm wondering if the leak was caused not by a bad seal but by a clogged crankcase breather. It was certainly plugged with the 20lbs of mud that was all over the bottom of the bike. The question is, what happens when this breater is clogged? Will the presurized crankcase blow oil out the c/s seal? What do you guys think?