Can Windshield Washer Fluid Be Used as a Substitute for Antifreeze?

[McRowan]

Windshield washer fluid cannot be used as a substitute for antifreeze. Antifreeze is designed for the engine cooling system and does not possess the cleaning or other functions associated with windshield washer fluid. Windshield washer fluid is primarily used for cleaning car window glass to remove surface stains, and similarly, it is not suitable for use as a coolant. Antifreeze prevents the coolant from freezing when the car is parked in cold winter conditions, which could otherwise cause the radiator to crack or damage the engine cylinder block. The full name is antifreeze coolant. The functions of antifreeze are: 1. Preventing scale buildup to avoid reducing the radiator's cooling efficiency; 2. Providing antifreeze protection, ensuring the car can continue to operate in low winter temperatures.

[MacAdriel]

Last time I was in a hurry on the highway and almost ran out of coolant, I nearly topped it up with windshield washer fluid. Then it hit me—that definitely wouldn’t work. Coolant is responsible for engine cooling, preventing freezing, boiling, and corrosion, while washer fluid is just for cleaning windshields, basically water with some detergent. Adding it to the engine would cause overheating. Last winter, a friend tried cutting corners and ended up clogging the engine’s water passages, having to replace the entire cooling system at a cost of over a thousand bucks. Now I always keep dedicated coolant on hand and check the level and color every six months. It should normally be green or pink—if it’s cloudy, it’s time for a change. Don’t cut corners; safety comes first. You’ll regret it big time if something goes wrong.

[LaLogan]

From a composition perspective, additives like ethylene glycol in coolant can withstand high and low temperatures, protecting metal components; windshield washer fluid is primarily water and alcohol, offering strong cleaning power but high corrosiveness. If added to the cooling system, metal pipes and radiators can easily corrode and deteriorate. As someone who enjoys tinkering with my old car, I've learned that coolant also needs to lubricate the water pump. Replacing it with washer fluid can cause significant pressure fluctuations, potentially damaging the pump, and freezing in sub-zero winter temperatures is even riskier. If temporarily out of coolant, it's best to dilute the old coolant with distilled water as a stopgap rather than using improper substitutes. Regularly testing the freezing and boiling points during maintenance can help identify issues early.

[MorganLynn]

Using windshield washer fluid as a substitute for coolant poses significant safety risks: when the engine overheats, it can boil, emit smoke, or even cause pipe bursts, leading to sudden engine shutdown while driving, which is extremely dangerous. In winter's low temperatures, it can freeze and expand, potentially cracking the cooling system and causing leaks, resulting in costly repairs. I've encountered similar cases where a small mistake led to accidents. It's better to develop a habit of keeping a bottle of standard coolant in the trunk—it's affordable and reliable.