Nothing to do with freezing, but two things they normally do (other than annual maintenance stuff like impellor, etc.) is fog the cylinder walls with rust inhibitor and change the engine oil so that any water, etc. in the oil doesn't hang out in there all winter.
I hear that so long as you run the engine once a month or so, you don't need to fog or charge the battery, etc.
As far as oil goes, it's kind of hard to change the oil in the fall (for the winter) when you use the boat in the winter, ya know? In the past, I've ended up doing it in January.
(Message edited by toyotafreak on September 30, 2005)