Can You Add Water to Car Coolant?

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It is not recommended to add water. It is advisable to use antifreeze as the circulating fluid for the engine to ensure optimal heat dissipation, effective cold and frost protection, and to maintain the engine's good working condition. Below are some relevant details: 1. General antifreeze formula: 50% pure water, 40% methanol, and 10% other substances, including dyes, corrosion inhibitors, and descaling agents. 2. If you frequently top up with pure water or tap water, over time, it can create a vicious cycle. The boiling point of water is 100°C, while antifreeze typically has a boiling point about 10°C or more higher. Adding water causes it to deplete faster. 3. The normal operating temperature of a car is around 90°C, often nearing 100°C for short periods, leading to faster evaporation and natural depletion. Therefore, irregularly adding water can negatively impact the engine's cooling cycle. Additionally, it is less effective for cold and frost protection in winter and can increase engine wear during cold starts.