I agree with FFin. A good friend of mine does it differently, he simply starts his motors at least every other month and lets them run for 20 minutes at idle (he has a large, heated shop for boat, blower, mower and tractor storage). He always treats his fuel with Stabyl. His snow blower started up yesterday and ran for 20 minutes (I don't want to think about snow just yet).If all motors are equal usually it's before an extended period on non use, like winter storage.