Drained my radiator for my Supercharger install and was debating on using Royal Purple - Purple ICE. Is it worth using? I am in Texas where it gets damn hot during the summer.
You should run the least amount of antifreeze possible. The following chart shows you the freezing temps based on antifreeze percentage.
35% antifreeze will get you a freezing temps around -10*f. This is well below the coldest I ever see in Austin(central Texas) even if you were to factor in wind chill.
Also you can try water wetter, but usually a higher water percentage will give you better cooling with out spending extra on additives.
Antifreeze is also to prevent corrosion, not just prevent freezing, something to keep in mind with all the various alloys in the cooling system. They don't always play nice together.
Aside from the corrosion inhibitors in the coolant the boiling point of distilled water is much lower than water/coolant mixes.
Keep in mind that the coolant system is pressured, which raises the boiling point of the liquid inside.
20/80 antifreeze/water here with a splash of Purple Ice, but look where I live. Watch the amount of additive you use also, to much equals foam. Ask me how I know, lol.