When a certain temperature is reached, the thermostat opens allowing liquid coolant to move through the engine transferring heat to the coolant from the engine block. A coolant is a fluid mixture of chemicals including, corrosion inhibitors lubricant and in some instances antifreeze, that allows heat to be absorbed while raising the boiling point. The coolant passes, gathering the heat as it flows through specific engine components, preventing overheating. The hot coolant then returns to the radiator, where it is cooled by air flow entering the engine compartment before returning to the engine to restart the process. Coolant temperature is crucial because it helps maintain engine temperature, which reflects ideal performance. As it blows air across the coolant, the radiator cools. The radiator circulates coolant through thin metal fins, allowing heat to escape to the air outside your vehicle. In most instances, a fan may blow air across the radiator, moving hot air out of your vehicle.