Boat shops up here run RV type anti-freeze through the motor when winterizing. I'm not sure where you got your info Mike, but RV anti-freeze protects to -50F at full strength without mixing. The coldest actual temp that I know of in VT since I have been here is -55F that was in the northest part of the state. The coldest temp that I have been frozen in is -30F. Now if you add in wind chill....it's still freakin' cold!!
Bob G.