Can coolant be mixed with water?

[OJosie]

Coolant should not be mixed with water, as it can easily cause scaling and affect the boiling point in summer, leading to overheating. Functions of antifreeze: Antifreeze does not cause corrosion to the engine cooling system and also has anti-corrosion and rust-removal functions. The boiling point of water is 100 degrees Celsius, while high-quality antifreeze coolant typically has a boiling point above 110 degrees Celsius, preventing overheating during summer use. Premium antifreeze is made with distilled water and contains anti-scaling additives, which not only prevent scale buildup but also help remove existing scale. Antifreeze replacement cycle: Generally, antifreeze should be replaced every 2 years or approximately 40,000 kilometers. Some luxury cars may have extended intervals, with antifreeze replacement cycles reaching up to 10 years or 200,000 kilometers. For vehicles that run for long periods, such as taxis, an annual replacement is sufficient.

[StElijah]

I've been driving this classic car for over a decade and always do the maintenance myself. The topic of adding water to coolant is crucial, especially for those of us who frequently drive on highways. Adding water short-term is fine—like topping up with purified water in an emergency when coolant is low to prevent engine overheating and stalling. But long-term use of tap water or regular water is a definite no-no. The minerals and impurities in water can accumulate and calcify in the pipes, leading to rust corrosion in the radiator and engine components. In summer, high temperatures cause rapid evaporation, and adding water may swell the cylinder block. Winter sub-zero temperatures are even worse; without antifreeze, pipes can crack or even ruin the entire cooling system. A good solution is to buy dedicated coolant or a 50/50 mix with distilled water—it contains additives to resist corrosion and regulate boiling points, protecting your car for longer. Remember to regularly check the coolant level and color changes in the reservoir—it’s cost-effective and safe.

[OKate]

As a young driver who just got my license, I've been learning about car knowledge. The issue of adding water to coolant should be viewed rationally. Coolant is mainly composed of ethylene glycol and water, designed to prevent freezing, boiling, and rusting. Simply adding water disrupts this balance. Chlorine and iron ions in ordinary tap water react at high temperatures, causing electrolytic corrosion of metal components. Adding a small amount of distilled water for short-term emergency use is acceptable, but long-term addition will significantly lower the boiling point and increase the risk of engine seizure. Even worse, water quality differences affect pH levels, leading to corrosion that clogs pipes and increases maintenance costs. I recommend using pre-mixed coolant or adding distilled water for adjustment, while also paying attention to changes in ambient temperature. During spring and summer, cars are used more frequently, putting greater pressure on the cooling system; in winter, the need for antifreeze is higher, so it's safer to replace it with pure coolant in advance. Safe driving depends on these small maintenance details.

[DiKimberly]

I often help friends with car issues, and cooling system problems are the most common. It's best not to add tap water to the coolant, as the impurities and minerals in the water can cause sediment buildup on the inner walls of the radiator, leading to rust and wear quickly. In an emergency, adding a bit of purified or distilled water can hold for a while, but you should visit a repair shop soon to replace it with proper coolant. Standard coolant contains anti-corrosion agents and wetting agents; diluting them with water reduces their effectiveness, lowers the boiling point, and may cause overheating. The freezing point rises, risking pipe bursts in winter. When checking the coolant, observe its color and concentration—cloudiness or low levels require immediate attention. A cost-saving approach is to buy distilled water and mix it with coolant according to the manual's specified ratio. Safety first—don't risk major issues for minor savings.