Looking at the service manual for my 06 CRF450 I came across this. I can't recall ever checking what the manufacturers recommend with maintenance, I have always just gone with the standard, change the oil and filter every couple rides, make sure your air filter is clean, grease your bearings every once in a while, etc.... But this states oil/filter changes every 15 hours? Am I changing my oil way too much? Also, a new piston every 15 hours? new chain every 7.5 hours? How closely should one follow this, on the one hand, if i can safely change my oil less that would be nice. On the other, id rather not tear open the top end every year.