I bought this a Wal-Mart. Blew out my lines a month ago and added the anit-freeze into the lines.
Packing up for the trip south. The anti-freeze half-empty was left outside next to the trailer. It has been below freezing pretty much for the entire month. However, it has NOT been below zero.
I picked it up to put into the garage and it was slushy, almost frozen solid. We shall see in a couple of days whether I have lost any water lines.
I suspect it would be a rock frozen at -50F.