Reply to your answer: as you said that "nothing will happen. It just drain out from the "overflow tub"!
But there is no overflow tub or any thing else to let it drain out. There is only a close reservoir with sealed cover with opening cap on the top!
Moreover, I do believe that, in a very down temperature of cold freezing weather, the antifreeze will be frozen and expend (as any other liquid expends in freezing down temperature) and that is enough to cause the reservoir to crack and be destroyed!
Monday, November 17th, 2014 AT 2:40 PM