What Happens If You Put Windshield Washer Fluid in Your Coolant? Let’s Find Out 

You just mistakenly put windshield washer fluid in your coolant reservoir. This happened due to misplacement. Because the portals for washer fluid and coolant are placed beside each other.  

But, however, you’re wondering now what happens if you put windshield washer fluid in your coolant?

Well, worry not. Because this contamination has little to no side effects at all. You might not sense anything other than the engine being a bit rough. The car will also run without any difficulties. However, the coolant might turn into gel because of reacting with washer fluid.

Well, this was just a short intro of the events that will follow if you put washer fluid in the cooling system, But there’s more to it.

To know more about the aftermath of what happens read along!

Can You Put Windshield Washer Fluid in Your Coolant Reservoir?

No, you can’t put windshield washer fluid in your coolant reservoir system. Antifreeze is the product specified to use in your car’s coolant reservoir. It keeps the engine warm and cold as per requirements and weather demands.

Windshield washer fluid is mainly used to keep the front glass of your car clean. It provides you with better visibility by melting ice and keeping the windshield clean. 

Source: driving-tests.org

The main ingredient for antifreeze is ethylene glycol. Whereas windshield wiper fluid is mainly composed of methanol. Both of the products are very harmful and toxic to human health.

Moreover, there are harsh cleaning agents in the washer fluid. It can technically cause corrosion of the metal parts if spilled out of the reservoir. It can also damage the gasket, water pump, and other components of the cooling reservoir.

The radiator fluid needs to be changed once in a while for the engine to function properly. Mix half part of the fluid with half part of the coolant to make it work.

You can compare your situation with something similar to an event. For example, when people mistakenly put transmission fluid in oil. This is far worse than mistakenly putting washer fluid in a coolant reservoir. 

Here, you will have to open the whole brake system and check from the beginning. To get the contaminated fluid out, you will have to replace all the rubber seals. Therefore the previous mishap is not much of a big deal if you just drain the fluid out initially.

You can always try out our recommended Antifreeze for a change! Take a look at them:

Zerex G05 Phosphate Free 50/50 Prediluted Ready-to-Use AntifreezeAdd to Cart
Valvoline Multi-Vehicle 50/50 Prediluted Ready-to-Use AntifreezeAdd to Cart
PEAK PXAB53 Antifreeze CoolantAdd to Cart

You should try these antifreeze to keep your engine running smoothly.

4 Consequences of Putting Windshield Washer Fluid in Your Coolant

One of the common mishaps with cars is putting windshield washer fluid into the coolant reservoir. People get confused and get it mixed up. This mainly happens because the coolant reservoir and the windshield fluid portal are next to each other.

Here are 4 conditions that you can face if you put windshield washer fluid in the coolant

  1. No Potential Harmful Effects

A windshield washer fluid is mostly composed of water. Thus, even if you accidentally put windshield washer fluid in coolant, you won’t witness any side effects. This is applicable only when you put a very small amount.

As it contains water,  it will simply evaporate when the engine is heated. The remaining chemicals will not affect the existing antifreeze or the vehicle’s cooling system.

  1. The Coolant Will Condense

Along with water. Windshield washer fluid solution also contains methanol in small amounts. Now when poured into the coolant reservoir, it acts with the existing antifreeze. For this reason, it leads to the coolant turning into gel-like consistency from the liquid.

It also teaches you to never mix one antifreeze with the other. For example, You should never mix traditional antifreeze with GM Dexcool. It is harmful and very costly to repair and fix it. 

You should only use the specific antifreeze suitable according to your reservoir. It keeps your coolant reservoir healthy and far away from malfunctioning.

  1. Clogging the Coolant Line Or Engine

There is a little amount of soap present in the Windshield Washer Fluid. Therefore, when the coolant gets hotter the washer fluid starts boiling off. It also expands due to heat generation. As a result, it leads to the radiator or coolant lines becoming clogged.

For this reason, if you ever put windshield washer fluid mistakenly in the reservoir just flush. This will help you to avoid any harmful side effects. 

Source: cars.com

  1. Loose Anti-Freeze Protection

Antifreeze is used in our car’s coolant reservoir. It prevents the engine from heating up during hot weather. And it also helps to maintain it during winter by preventing it from freezing.

When you use windshield washer fluid instead of antifreeze, it will provide some anti-freeze protection. Because it contains alcohol in it. Alcohol will normally boil when the engine warms up. But when it does, it will pass through the radiator cap. You will lose some of your coolant and antifreeze protection because of this.

These are all possible situations you can face if you put windshield washer fluid in the coolant reservoir.

4 Measures to Adopt After You Mistakenly Put Windshield Wiper Fluid In Your Coolant

In the event that you have not run your car since adding the washer fluid, you can just flush it. It’s as simple as cleaning your fuse box terminals. You just have to follow these simple steps

  • You can utilize a turkey baster or fluid transfer tool to drain the unwanted fluid from your reservoir.
  • You have to fill the reservoir with water. 
  • After that, you have to flush out the water as well and empty the reservoir.
  • Now you need to fill your reservoir with ½ part of antifreeze with ½ part of water. You have to use the specified coolant from your Owner’s Manual. 

Source: rxmechanic.com

But if you have already used your car, the procedure will be different. You must take your car to a workshop and request a coolant system flush and refill. If you remove the fluid at once, there will be no potential side effects or no effects. 


Can you replace water with washer fluid in your car?

Yes, you can use water in place of washer fluid to clean the windshield in your car. But if you’re using water, you must use distilled water. Because open water has specific minerals that can cause washer jets to get jammed. It will also leave residues on glass. 

What is the price of a coolant flush?

According to the standards of highly rated mechanics, it typically costs between 100-150$  to get a coolant flush, a conditioner, cleaner, and four gallons of coolant. You can also take help from CostHelper.com to estimate the cost. A radiator flush mostly costs 50$ to 150$  at a standard shop, on average around $99.

Can you pour windshield washer fluid if the car is hot?

Yeah, you can pour washer fluid while the car is hot. But you have to be careful that you don’t overfill the reservoir. Because the fluid expands when it’s heated. When the fluid is heated the pressure from the reservoir will make it crack. It will also spill and leak if there’s a lot of fluid present there.


That was our take on what happens if you put windshield washer fluid in your coolant. 

It’s best that you don’t replace it with the antifreeze specified for your coolant system. If you are stranded on a road and have an emergency, you can use it. 

Best of luck!

Robert Lozano

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