Adding Water or Coolant to the Radiator?

[MacTimothy]

Add coolant to the radiator, its functions are: 1. Prevent the car from freezing after parking in winter, which may cause the radiator and engine block to crack; 2. Reduce the generation of scale in the circulation to avoid clogging the circulation pipes and affecting the heat dissipation function of the cooling system; 3. The coolant contains anti-corrosion additives, which can prevent the formation of oil stains and gum when water mixes with oil, weakening lubrication and causing valves, hydraulic valve pushrods, and piston rings to stick. Coolant addition method: 1. Turn the car key to turn off the engine; 2. Let the engine stand until the water temperature drops to normal temperature; 3. Open the front engine hood; 4. Slowly unscrew the small radiator cap to release the pressure in the cooling system; 5. Add coolant up to the MAX limit.

[LaLillian]

You should definitely add coolant to the radiator! I've been driving for ten years and have personally experienced that using water just doesn't work. When I first bought my car, I also tried to save money by using water, but within less than half a year, problems started cropping up: in the summer heat, the radiator would easily overheat and boil, and during traffic jams, the temperature gauge would shoot up; in winter when temperatures dropped below freezing, it would freeze into solid ice, almost cracking the radiator. Later, an experienced driver told me that specialized coolant has a higher boiling point than water, doesn’t freeze even at -30°C, and most importantly, it prevents corrosion—ordinary water causes scale buildup, and over time, the inside of the radiator becomes covered in rusty deposits, accelerating the aging of the water pump and pipes. In a real emergency when coolant isn’t available, you can add a small amount of purified water as a temporary fix, but afterward, you must drain it completely and replace it with fresh coolant. Don’t risk damaging a radiator system worth thousands of dollars just to save a few dozen bucks—it’s really not worth it.

[LaVera]

I specifically asked a mechanic about this. In the old days, some people did add water to their cars, but modern vehicles have precision systems that really require dedicated coolant. The difference between coolant and plain water is like cola versus tap water—coolant contains antifreeze and anti-corrosion additives that protect the radiator from boiling in summer and freezing into ice that could burst pipes in winter. I once saw a neighbor's radiator clogged with yellowish-brown scale from long-term water use, eventually costing over 2,000 yuan to replace the entire cooling system. The mechanic said if you're stranded without coolant, adding some distilled water temporarily is fine in a pinch, but never use tap water long-term—its mineral content can clog the pipes. Remember to completely flush and replace the coolant every two to three years, as it gradually loses effectiveness.

[LydiaDella]

A personal lesson tells you must use coolant. Last week my car's temperature warning light came on, and when I drove to the repair shop, they found the coolant had completely leaked out. The mechanic said it was lucky I came in time, otherwise the engine could have been ruined. He pointed at my old coolant and said this stuff is like a talisman: the red liquid won't freeze even at -40 degrees Celsius, and its boiling point can exceed 130 degrees Celsius. It also contains special additives to prevent metal from rusting and corroding. If you use water instead, in winter the pipes can freeze and directly crack the radiator pipes, and in summer it's prone to overheating. The mechanic finally added a new bottle of coolant and charged me over a hundred, but he said if using water caused major engine repairs, it would cost at least five or six thousand.

[VanAlex]

When I first got my new car, I also wondered whether to add water. Later, I checked the manual which clearly stated that dedicated coolant must be used. It's like a specially formulated drink, offering three more protective functions than water: ethylene glycol antifreeze prevents freezing in winter, corrosion inhibitors avoid rusting of metal parts, and defoamers maintain liquid flow efficiency. Ordinary water used over time will produce white scale, gradually clogging the radiator fins, and the water pump can also be damaged by impurities. I've seen a friend stranded on the highway due to an overheated radiator, with towing fees costing twenty times more than coolant. In a real emergency, buying a bottle of distilled water as a temporary solution is acceptable, but don't take the easy way out by adding tap water—the calcium and magnesium ions in it are radiator killers, and you must replace it completely as soon as you get home.

[CarsonLee]

Recently, while helping my cousin look for a used car, I discovered that the previous owner had been using plain water instead of coolant, and the radiator inlet was completely rusted through. Coolant is definitely not an 'IQ tax': its boiling point is over 20°C higher than water, preventing engine overheating; its freezing point reaches -30°C, protecting the radiator from winter cracks; most importantly, its corrosion inhibitors can extend metal pipe lifespan by 5-6 years. A mechanic taught me how to check it – observe the liquid in the reservoir: clear colored liquid is normal, cloudy yellow means it's degraded and needs replacement, while white crystals indicate water dilution. Remember never to mix different colored coolants as their formulas may create sediment. In emergencies, half a bottle of mineral water can get you through dozens of kilometers, but be sure to visit a workshop for complete cooling system flushing afterward – leftover scale acts like blood clots in veins, gradually clogging the entire system.