Your vehicle’s coolant system helps to keep engine heat at recommended levels for your car’s optimum operation. This system includes multiple components: a radiator, a water pump, an overflow reservoir, thermostat, temperature sensor, hoses and channels in the engine itself to remove the heat. The thermostat opens at a pre-designated temperature during engine operation to allow the coolant in. Any number of causes can reduce the coolant levels in your car.
Most overflow reservoirs come equipped with a small tube that allows the coolant to escape if the engine gets hot enough and the coolant expands past the full mark on the overflow reservoir. This can happen on hot days when you also run your air conditioner. Because of this, you need to check the reservoir level periodically to ensure coolant is between the minimum and maximum marks on the reservoir. Use the recommended mix of coolant and water for your vehicle and fill to this location.