Prevents Freezing and Boiling

Pure water can be corrosive to engine components, so it should not be used to cool an engine. Additionally, it freezes at 32ºF (0ºC) and boils at 212ºF (100ºC). If coolant freezes, it will expand and eventually crack the engine block. Also, the engine can run hotter than 212ºF (100ºC) and boiling causes problems. The solution to this is to use an antifreeze/water mixture. In most climates a 50% antifreeze to 50% water mixture is recommended all year. This will give the coolant a freezing point of -34ºF (‑37ºC) and a boiling point of about 226ºF (108ºC). When the cooling system is under pressure from the radiator cap, the boiling point raises to about 265ºF (129ºC) when the mixture is 50/50. In a severely cold climate, 60% antifreeze to 40% water is necessary. It is not recommended to use pure antifreeze in the cooling system. Manufacturers commonly recommend a maximum of 70% antifreeze to 30% water when using standard antifreeze. The antifreeze/water mixture carries the best properties. Note: Use only distilled water when mixing.