50% Ethylene Glycol, 50% demineralised water. This is a eutectic mixture with a freezing point of -65F or -54C, so very close to a frozen radiator.....
The Canadians have block heaters, electric coolant pumps and radiator shutters to deal with very low temperatures. The car is warmed up to operating temperature before leaving the garage....
Pure ethylene glycol freezes at +5F or -15C.
