well that is like asking how high is up.depends on how many hours on the motor,what rpm's,what kind of oil ya use,what kind of boat,etc.i know guys that blow em up every 2 weeks,and i know guys that have over 300 hours on them and have never taken them apart.alot has to do with how you take care of it but i think john tiger said anything over 200 hours and your doing good.