Is it okay to add water instead of coolant to the radiator?
4 Answers
It is not advisable to add water instead of coolant to the radiator. Since water has a high freezing point, it can freeze in winter and cause damage to the engine. It is recommended to use coolant instead of water. Coolant prevents the freezing of the liquid in cold winter conditions, which could otherwise crack the radiator or damage the engine cylinder block or head. It offers excellent performance in preventing freezing in winter, boiling in summer, and resisting scale and corrosion throughout the year. The car radiator, generally referring to the heat exchanger, is part of the car's cooling system. The radiator in an engine's water cooling system consists of three parts: the inlet chamber, outlet chamber, main plate, and radiator core. Installation methods include same-side inlet and outlet, opposite-side inlet and outlet, and bottom inlet and bottom outlet.
Having driven for decades at my age, it's not advisable to just add plain water instead of coolant in the radiator. Water easily freezes below zero degrees in winter, and when ice expands, it can crack the radiator or even the engine block. Repairs would cost at least hundreds or thousands of yuan, not to mention the risk of breaking down midway. Summer is even worse—with a boiling point of only around 100°C, water will immediately boil when the engine gets hot, leading to overheating damage. The cost of replacing an engine is enormous. Coolant is specially designed for vehicles, with a boiling point above 130°C and a freezing point as low as -40°C. It also contains anti-rust and anti-corrosion additives to protect pipes and the water pump from rusting. Long-term use of water causes mineral deposits that clog the radiator, drastically reducing cooling efficiency and doubling the risk factor. Safe driving shouldn’t be taken lightly—don’t skimp on coolant. Regularly check fluid levels and concentration for long-term peace of mind and savings.
With over a decade of experience in auto repair, I've noticed many people try to save money by using plain water instead of coolant in their radiators, leading to severe corrosion issues. Water contains oxygen and impurities that oxidize metal components, such as aluminum or iron pipes inside the radiator, causing rust that gradually perforates and leaks. The water pump is also prone to corrosion and seizing. Coolant contains special additives that form a protective film to prevent rust and avoid scale buildup. Using only water reduces cooling system efficiency, causing engine temperature to spiral out of control. Overheating can warp or destroy components, costing far more in repairs than the initial savings. I recommend regularly testing coolant concentration to ensure proper antifreeze and anti-boil functionality. Don't risk major damage for minor savings—proper maintenance is key to long-lasting vehicle performance.
For ordinary families, using plain water in the radiator instead of coolant may seem like a cost-saving measure, but it actually leads to losses. Water easily causes rust and corrosion in the cooling system, leading to radiator leaks or pipe bursts over time, with repairs costing hundreds of yuan, while a bottle of coolant only costs a few dozen. Moreover, water has a low boiling point in summer, causing the engine to overheat during high-speed driving and damage the pistons; in winter, it freezes and can burst components, making towing fees even more painful. Coolant, on the other hand, has a high boiling point to prevent overheating, doesn’t freeze in low temperatures, and protects metal parts from aging. It’s recommended to replace it regularly as per the car manual—normally every two years—which is a small investment with great returns. Don’t cut corners for small savings; in the long run, proper maintenance lowers costs and ensures safety.
