I have a yanmar 2gm20f and to winterize the engine I run 4 or 5 gallons of antifreeze through the engien. The boat is in Wisconsin so it is pulled out each year. I am wondering if any one drains the raw water system vs running antifreeze at the end of the season. Yanmar manual said to drain the raw water to winterize. There is a small drain for raw water side of the heat extchanger, small valve for muffler to drain and would need to remove water pump (good time to inspect). I did run antifreeze through the raw water system but this winter I did the listed steps as I am inspecting the heat exchanger and replacing some hoses on the raw water system. Draining was pretty easy not sure if the antifreeze is needed. Thoughts?