Yesterday I bought two gallons of Prestone antifreeze for my rpu. I bought straight, not premixed. Why would I pay for water when I can buy distilled water so cheap ? The straight was $ 17.99 a gallon, and the premixed was $ 14.99. They are raking in a lot of money for just selling us water.
The one I bought said for use in ALL systems, and since my rpu has an aluminum radiator, that is what I got.