We've been over this before, but I guess you missed it!
Anti-freeze is mainly composed of a glycol, wether it's propylene glycol, or ethylene glycol. Both do well, but are really designed to work in an environment where the coolant temperature is around 200 degrees, which is not our case...
30 degrees C is about average for water temp in a rig.
The additives is all we really need: adding anti freeze would only degrade the cooling ability of the water.
On the other hand, if you were cooling the coolant to a very low temperature (near freezing) then it's a whole other ballgame, where the glycols don't do well at all.
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