Can I Add Water to Coolant?
2 Answers
Coolant should not be mixed with water. Below are the details about coolant: Functions of coolant: Coolant is a liquid containing special additives, primarily used in liquid-cooled engine cooling systems. It offers excellent properties such as antifreeze in winter, anti-boil in summer, and year-round protection against scale and corrosion. Chemical composition of coolant: Over 95% of coolants used domestically and internationally are water-based ethylene glycol coolants. Compared to tap water, the most notable feature of ethylene glycol is its antifreeze capability, which water lacks. Additionally, ethylene glycol has a high boiling point, low volatility, moderate viscosity that changes little with temperature, and good thermal stability. Therefore, ethylene glycol-based coolant is an ideal choice.
I've seen many car owners damage their vehicles by using only water. While water can serve as a temporary emergency solution, it's absolutely unsuitable for long-term use. The cooling system is designed for specialized coolant, which contains anti-rust additives to protect metal components from corrosion and also raises the boiling point to prevent engine overheating. Using water can cause rust and scale buildup in the pipes, eventually blocking the channels and leading to poor heat dissipation that may result in engine seizure. Especially in northern regions during winter, when water freezes and expands, it can crack the radiator. From my experience, I recommend regularly checking the coolant level and topping it up with proper coolant when low—don't cut corners by adding pure water. Keeping a bottle of 50/50 pre-mixed coolant in your car is much safer, ensuring worry-free driving for ten years.