In cold weather, the engine and the coolant in it are colder. This causes the coolant to flow more slowly and take longer to circulate throughout the engine. As a result, the coolant has more time to absorb heat from the engine, and the engine may overheat. To prevent this from happening, the car's thermostat opens wider, allowing more coolant to flow through the engine. This increased flow of coolant helps to keep the engine cool, but it also means that more coolant is used up.
In addition, cold weather can cause the coolant to become more viscous, which makes it harder for it to flow through the engine. This can also lead to overheating, and the car's thermostat will open wider to compensate.
Finally, cold weather can also cause the car's radiator to become less efficient at dissipating heat. This is because the cold air flowing over the radiator is not able to absorb as much heat as warm air. As a result, the coolant may not be able to cool down enough as it flows through the radiator, which can lead to overheating.
For all of these reasons, a car uses more coolant in the cold than in the warm weather.
