To determine whether the coolant needs to be replaced, a comprehensive assessment can be made from multiple aspects such as colour, odor, impurities, freezing point, and service life. Normally, the coolant should remain clear and transparent; if its colour darkens, becomes turbid, or flocculent substances appear, it indicates contamination and requires replacement. If an acrid or pungent odor is detected, it means the additives have failed or deteriorated. When measured with a freezing point tester, if the freezing point is higher than the standard value for the vehicle's operating environment (e.g., ensuring stable boiling point in tropical regions), or if the pH test paper shows the pH value is below 7.5, the coolant should be replaced promptly. In addition, sediment adhering to the inner wall of the expansion tank or the illumination of the coolant warning light are also signals for replacement. It is best to replace the coolant regularly every two years, prioritizing original manufacturer or major brand products. Regular maintenance can prevent engine overheating, coolant passage blockage, and corrosion of metal components, ensuring the efficient operation of the cooling system.
