Guy's ...... there are only two things that really matter. One, is it corrosive? and two, does it contain coagulants like those in some automotive coolants. Otherwise have at it and report back! You could probably use Alpaca urine, .... i dunno. Tap water, hose water, etc, are eventually going to calcify, and lime up your little torch pathways. But i guess thats why they make CLR, and lime away. Some auto coolants have radiator coagulants to help guard against small leaks. RV coolant is a different formula. Distilled water, .... sure why not. As far as sub zero temps, .... god bless ya if you can weld in that enviroment! lol! If just occassional work, just dump the water when your done, what is it, ... 2 gallons of distilled?
Don't get me wrong here my friends, just bein a little tongue in cheek to lighten it up! There's lots of ways to skin a cat!