The radiator is a critical part of a car's cooling system. Cars are cooled by a two-part heat exchange; first, heat from the engine is picked up by the coolant fluid which carries the heat out to the radiator where it is passed into the air and out of the car. The fins of the radiator radiate this excess heat out so that when the coolant flows back to the engine, it is ready to pick up more heat. Without a radiator, the coolant would still absorb heat from the engine. The coolant would then become just as hot as the engine, resulting in excessive engine temperatures that will cause harm to the engine. It is important to follow outlined instructions when replacing a radiator and coolant, the only reason to deviate from the manufacturer’s recommended coolant and water ratio or suggested brand of coolant is an alternative radiator replacement, from which you should adhere to guidelines instructed by the manufacturer of the radiator.