Why does the coolant have to be checked for sufficient frost protection before winter begins?

It is important to check the coolant for sufficient frost protection before winter because if the coolant freezes, it can expand and cause serious damage to the engine’s cooling system. This can lead to cracks in the radiator or engine block and ultimately cause engine failure. Ensuring the coolant has the right antifreeze properties protects the system from freezing and therefore prevents costly repairs. The vehicle’s operating permit is not affected by the coolant’s condition, so that option is not relevant here.