How Much Coolant?
My guess would be close to 4 gallons total capacity.
Get 2 gallons of coolant and 3 gallons of distiller water.
If you need more than 4 gallons you can use some of the third gallon of water to top it off. You can add 1.5 quarts of the third gallon to the mixture and your result would be 40% antifreeze.
That should get you to approximately-5° F freeze protection.
What is your lowest expected temperature?
