What Happens If You Put Windshield Wiper Fluid In Coolant?

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If you are wondering what happens if you put wiper in the coolant, it’s more likely that you’ve already put some wiper fluid in the system. Though wiper fluid isn’t designed to be poured into the coolant, you shouldn’t be worried even if you do so.

Wiper fluid won’t damage the coolant in most cases. However, it can clog the radiator, blow the engine, and prevent the engine from operating if you don’t drain the reservoir. Luckily, you can recover from this error in plenty of ways, even in a home garage.

Read on to learn the consequences of putting wiper liquid in the coolant, why you shouldn’t do so, and how to avoid these silly yet common mistakes.

What Happens If You Put Windshield Wiper Fluid In Coolant?

Putting wiper fluid in the coolant is neither a big problem nor a good idea. The consequences of putting wiper fluid in the coolant depend on plenty of factors, including the ingredients, amount of wiper fluid, and further steps.

The windshield wiper brake fluid contains water that the car engine will cook off during warm-up. The other chemical contained in the solution might not affect the cooling system of the vehicle. However, the dangerous component of wiper fluid is a small amount of soap.

This component can expand easily if the coolant heats up and can clog the radiator as well as prevent the car from operating. As the water, alcohol, and soap in this fluid clear road grime, it can even blow the engine.

Despite this, some wiper fluids contain alcohol to offer antifreeze protection. But a hot engine can blow the alcohol through the radiator cap and leak the coolant. Even the methanol contained in the wiper fluid can damage the hoses and seals.

In terms of amount, if you pour a small amount, the engine will cook off most of it, and the remaining amount won’t affect the coolant or the cooling system of the vehicle.

However, if you leave the fluid for a few days and continue driving, it will turn gelatinous.Due to the chemical reaction between the windshield washer fluid and the coolant, the coolant will gel up.

What to Do After Putting Wiper Fluid into Coolant?

Based on the time since you poured the wiper fluid into the coolant and the next step, choose the best solution.

If you didn’t drive the car after pouring fluid into the coolant reservoir, use a turkey baster to suck the polluted fluid out of the coolant. Then put some water in the reservoir and drain it as well to make the coolant completely empty. After that, refill the coolant with water and antifreeze solution, preparing it at a 50:50 ratio or following the car’s owner manual.

Alternatively,  if you put a whole jug of wiper fluid in the coolant, drain it out by disconnecting the lower radiator hose. Then reconnect the hose and fill the coolant with the right antifreeze. Otherwise, the wiper fluid won’t possess the cooling properties required to cool the engine. In addition, the extra volume of the fluid will prevent sufficient antifreeze from being put into the system.

But if you’ve driven the car already, flush the coolant system and refill the coolant to remove the washer fluid from the system. If you can remove the material immediately, it won’t cause any substantial effect.

You shouldn’t worry about the remaining liquid in the coolant reservoir. It’s toxic but biodegradable. In addition, if you drop some fluid, simply dilute it with water.

Then refill the coolant with the correct antifreeze. If it is winter or your living area becomes too cold, check the coolant’s radiator cap using a hygrometer. That’ll help you retain the freeze protection.

Why You Shouldn’t Put Wiper Fluid in the Coolant Instead of Antifreeze?

First of all, wiper fluid and coolant aren’t the same, and these fluids are designed for different purposes. Using coolant in place of wiper fluid will increase the chance of damaging the vehicle’s paintwork. Conversely, using wiper fluid rather than antifreeze in the cooling system will put the engine at risk of coolant freezing in cold temperatures.

There are lots of differences between coolant vs windshield wiper fluid as well. The coolant, also known as antifreeze, prevents the engine from overheating during the summer. On the other hand, wiper fluid cleans the windshield and melts ice for better visibility during stormy and cold weather.

In terms of ingredients, the coolant mostly contains ethylene to prevent freezing and increase the boiling point. It also has a bit of cleaning power and is usually slimy to the touch.

Conversely, the wiper fluid mostly contains water and some alcohol to avoid freezing like coolant. However, the alcohol of the wiper fluid cut dirt and grease on the windshield as well as dry through evaporation quickly. So you can say both of these fluids prevent freezing, however using different chemicals.

How to Tell If It Is Coolant Or Windshield Wiper Fluid Reservoirs

The key reason for wondering what happens if you put wiper fluid in the coolant is that you might pour one instead of the other by mistake. So it’s worth knowing how to determine or check if it is a coolant or wiper fluid reservoir to avoid mistakes, further frustration, or damage. The easiest way to locate the wiper fluid container and coolant are to check under the car hood. Make sure the engine is cool, and don’t try to open the cooling system of the hot engine.

There should be “Coolant Reservoir,” mentioned on the coolant lid, or it should seem like a radiator. Some vehicles also specify the type of coolant system required. Apart from that, the most common sign is “hot,” which should be mentioned on the container.

Conversely, the washer reservoirs are extremely easy to locate. Simply look for the image of the wiper and windshield.


1. Can washer fluid damage your car engine?

The two main elements of washer fluid are water and alcohol, and these won’t damage your engine in most cases. However, you should drain the fluid immediately to avoid reducing the engine’s performance.

2. Can I pour wiper fluid into a hot engine?

According to most vehicles’ user manuals, you shouldn’t put washer fluid in the hot hybrid system. The reason is that the alcohol in the wiper fluid can cause a fire if it spills on the engine.

3. Can wiper fluid go in the coolant?

There is nothing to worry about if you put a little amount of wiper fluid in the coolant. Though it can prevent freezing the coolant, it has a certain container to go in and is intended to clean the windshield.

Final Words

After understanding what happens if you put wiper fluid in the coolant, hope you’ll be more careful when maintaining your car engine and avoid mistakes. But the fact is, this silly mistake won’t cost you immediately and severely, and you have some simple solutions to fix it.

However, it is prudent to pay closer attention and locate the appropriate container before pouring the appropriate liquid into it to prevent further mass. 

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