Should the Radiator Be Filled with Water or Antifreeze?

[SanAaliyah]

The radiator should be filled with antifreeze. The car radiator, also known as the heat exchanger, is a key component in the automobile cooling system, and its function is to dissipate heat. Below is some information about the radiator: 1. The coolant absorbs heat in the radiator, dissipates the heat when flowing to the heat exchanger, and then returns to the water jacket for circulation, playing a role in temperature regulation. It is an important part of the car engine. 2. Adding water to the radiator can cause scale buildup, corrode the engine block and radiator, and in severe cases, lead to radiator leakage, affecting cooling efficiency and damaging the engine. 3. Water freezes below 0 degrees Celsius, and when it freezes, it expands in volume, which can crack the radiator and damage both the radiator and the engine block. Water also boils at 100 degrees Celsius, evaporating in large quantities, which is not conducive to cooling.

[ORichard]

I once made the mistake of thinking it was fine to just add plain water to the car's radiator for convenience. Then one harsh winter, my car wouldn't start at all. After towing it to the repair shop, I found the radiator had frozen and cracked, nearly causing engine failure. The repair bill cost me over a thousand bucks. Since then, I've learned that radiators must be filled with coolant, not water. Water can freeze and expand in low temperatures, damaging components, while in high temperatures it easily evaporates and boils, leading to engine overheating. Coolant contains anti-corrosion additives to prevent rust and can handle extreme temperatures year-round. I usually use the green ethylene glycol-based type, which has a freezing point as low as -40°C and only needs replacement every two years. During routine fluid level checks, I top it up with a premixed solution—cost-effective and worry-free. Adding water is only a temporary emergency measure and must be replaced immediately afterward. Proper maintenance keeps your car running smoothly—don't learn the hard way like I did.

[MiguelLee]

As a car enthusiast, I know you should never fill the radiator with plain water. Water causes corrosion, rust, and scale buildup inside the engine, damaging the cooling system over time. Antifreeze is the proper solution—it not only prevents freezing but also raises the boiling point to avoid overheating. When choosing a formula, pay attention to the color and freeze-point rating—for example, I use blue antifreeze rated for -30°C in northern regions. Replace it every two years, and top it off with matching antifreeze if the level is low during routine checks. Tap water is worse due to impurities, and distilled water is only a temporary fix. A well-maintained system ensures better heat dissipation and prolongs the engine's overall lifespan. Putting in a little extra effort makes the driving experience much smoother.

[SanHenry]

Add antifreeze to the radiator, not water. Water can freeze and cause damage or evaporate and become ineffective. Antifreeze prevents freezing and corrosion, protecting the components. Purchase automotive-specific antifreeze and add it directly to the radiator cap, topping it up when levels are low. Regularly replace and check to ensure the system remains in good condition. Adding water carries significant risks and should only be used as an emergency backup. This practice helps avoid accidents—safety comes first.