[cwl1979]

50/50 if you don't get outside temps below -20F. 60/40 from -20 to -50F. And use 70/30 If your crazy enough to be colder than that. Whatever color you go with when you get the chance I would recommend keeping the generator with the same coolant. Easier to just have a gallon for spare and no confusion as to what goes where. My Aquahot also has the same coolant as the fresh water coil is wrapped around the outside of the tank and can not come in contact with the coolant.
Personally I run shell red coolant in everything.