I use the same stuff as you pour in your car's radiator for cooling the engine . i have the same fluid in my machine for over 3 years now. No problems at all.
maybe the effectiveness is a few percent lower than distilled water but then your cooler has to work a bit harder maybe.. My temperature is stable at 15 degrees, also after two hours cutting at 90% power..
But i don't care if anyone else stick to destilled water and want to change that every X weeks..... i stick to coolingfluid.. preferably the blue one as it mathes the color of my machine

... just kiddin' : that's what i bought a few years ago, i think it comes in purple and green aswell... same shit.. Mines can be used till -28 degrees celsius..
Kees