What antifreeze do you guys use to winterzize. I bought some of the pink Marine/RV antifreeze and ran it through the cooling system via a 5 gallon jug connected to the flusher. I thought I would test the antifreeze by placing a containter of it in the freezer to see if was actually good to -50. Not quite, started to freeze up in my freezer and it only gets to 0. I think I'm gonna be safe and order some -100 antifreeze. I live in IL and it is very likely it will be below zero a couple times this winter.