antifrieeze
I start mine, without water, then turn on water, warm it up a bit, then kill water, shut off engine. restart engine, blow out water...
then fill a 5 gallon bucket with 2 gallons of that RV stuff, and I have a water pump... hook pump to ski. start engine. start pump... run 2 gallons through engine w/engine on, when pump runs dry i shut off the engine...
then pull plugs, spray fogger in pistons, then replace plugs, pull battery for winter, wash whole thing, dry, cover, and cry because it will be 195 days from today until I take that cover off...