I agree with embrey,,change them out every 2 yrs,,,BUT this is the thing that kills the pumps,,DON`T EVER START YOUR MOTOR WITH OUT MUFFS!!!!!!!!!! I just sold my Stratos and the guy wanted to trade in his V-hull to me and was tellling how good his motor was,,he started it up with out muffs or water and ran it and rived it up for 30 sec`s that killled it for me,,,dumbass! It don`t take but a few sec`s to burn a pump up,,,,never,,i mean never start your motor with out water! I work on boats for a living and these kinda people i like,,,now something esle I`ve found out is that for older motors ,,90 on backmmand like late 70`s and early 80s the pumps are higher priced. I replace pumps for 100.00 bucks incudeing the empeller while you wait,,,,