Depends on how hard you spin it. The impeller can be spinning as high as 70,000 rpms and up. The bearings don't last forever and the oil seals go bad and the impellers sometimes need to be rebalanced. Some models of superchargers also use a kevlar belt inside instead of a gear driven mechanism. This belt wears out and starts to slip eventually.how oftan do u have to have a supercharger serviced??