To what level should the coolant be filled?
2 Answers
The coolant should be filled to the level between the upper mark MAX and the lower mark MIN. If overfilled, the coolant may overflow from the pressure relief valve due to thermal expansion and contraction. There is usually an overflow reservoir for excess coolant storage, so exceeding the mark slightly is not a big issue. However, it is still better to fill it to the appropriate level since the coolant will naturally evaporate. If the coolant level is found below the MIN mark on the radiator, it is necessary to promptly replenish it with the same color, brand, and model of coolant. In emergency situations where coolant is temporarily unavailable, purified water can be used as a substitute. However, it is recommended to promptly check the specific reason for the coolant loss and replenish or replace the coolant as soon as possible to avoid unnecessary damage to the engine caused by insufficient coolant.
I find the expansion tank in the engine bay is the most suitable place to add coolant. It's a transparent plastic tank with Min and Max level markings—always add between these lines. Having driven for over a decade, I always wait a few minutes for the engine to cool before topping up for safety. Just pop the hood to locate it. Never overfill to the brim, as it may cause coolant leaks or excessive system pressure, nor add too little to risk engine overheating. Regularly check for sediment or cracks at the tank base, which indicate potential radiator clogging or aging. Monitor the mixture ratio in summer and winter—low concentration risks boiling/freezing; a refractometer test is ideal. If the tank is empty, first inspect for leaks or water pump issues before refilling.
