I know how to winterize my motor. I'm just curious about why I do certain things before winter instead of just waiting till next spring before taking the boat out.

Fogging and stabilizing makes sense to me, but is there a reason to change out the lower unit fluid before winter instead of just doing it in the spring? The same goes for the motor oil.

Thanks for helping to satisfy my curiosity.

-Chuck

The reasoning behind changing the lower unit fluid is to make sure that there are no seal leaks which have let water in and can freeze and break the housing.  I do mine every 6 months just to be on the safe side.  It is a lot cheaper than a $4000 lower unit.