It's not clear from your post whether you will be in New York
for the winter or just won't leave until early in the winter. For the closed component of the cooling system, I agree with the other posters that you should use the manufacturer's recommendation for type of antifreeze and change interval. If the boat
is in the water, you're not leaving it for weeks at a time, and you're not upstate where the weather
is severe, you shouldn't have to winterize the raw water
circuit. If you decide to haul or to winter over, you should use the pink environmentally friendly stuff for marine
and RV use to prevent freezing in the raw water circuit. It's easy enough to put a gallon or two of antifreeze in a bucket, pull the hose off the (closed) raw water through hull
and use the hose to pull the antifreeze out of the bucket and through the raw water circuit. If circumstances require that, you should also be draining your fresh water system and your hot water tank. A royal PITA that is part of the joy of living in the North.