Failure to replace antifreeze for an extended period will cause severe degradation of the cooling system's performance. First, the anti-corrosion additives in the antifreeze will gradually deplete, exposing internal engine metal components such as the cylinder block, radiator, and water pump impeller to a corrosive environment, which may lead to rust and the formation of sediment that clogs water passages. Second, the physical properties of the antifreeze will deteriorate: a rising freezing point can cause the coolant to freeze and expand in cold conditions, cracking the radiator or engine block, while a dropping boiling point will make the coolant vaporize prematurely under high-temperature operation, reducing heat dissipation efficiency and causing engine overheating. Additionally, the increased viscosity of oxidized and degraded antifreeze will impede its normal circulation in the cooling system, increasing the water pump's workload and accelerating the aging of rubber hoses. It is best to replace the antifreeze that meets the original equipment manufacturer (OEM) specifications every 2 years or 40,000 kilometres. When replacing, the old fluid must be completely drained and the cooling system cleaned to avoid mixing antifreezes of different formulations. Notably, although some long-life antifreezes are claimed to last 5 years, it is still advisable to shorten the replacement interval in high-temperature and high-humidity environments to ensure the cooling system's efficiency.
