LOL. This is just too funny.
The name Anti-freeze. It's usage in a car loop is... Ohh I know maybe you don't. So I'll answer this old many times asked lame question.
Anti freeze keeps the water in a car loop from boiling. It also, depending on the temps and mixture levels keeps the water from freezing.
Is your watercooling loop going to be above 212F or below 32F temps? LOL NO. cars run water temps at over 150F, up to 200+. We run WC at 110 +/- 20F. Gaaaaa. Stupid internet.
In a car loop you can have steel, alumininum, copper, and brass in a loop. So they add anti corrosive chemicals.
I don't know if you have really done any research or been on watercooling forums for more than 3.2 minutes. I've spent years.
In a modern watercooling loop we use distillled water and a biocide. You can figure out the specific heat properties of pure water vs any other fun stuff you want, pure water wins. We need no below freezing or anti-corrosive liquids.
You could see a drop in temps, but it's in %. You just don't need antifreeze, you need biocide. At the 6 months drain please get rid of the antifreeze.
BTW, your antifreeze doen't stop algae or other nasties from growing.
i4ynu, you really need to hang out at a few other forums and read a lot..............