Did You Accidentally Put Windshield Fluid in Coolant?

It’s pretty common to mistake the coolant reservoir for the washer fluid reservoir for some reasons. In most vehicles, the coolant reservoir and the windshield fluid reservoir are placed side by side, making it easy for one to mistake one for the other. Another reason car owners mistake them is that both fluids look alike.

Did you accidentally put windshield fluid in coolant reservoir? If yes, don’t panic. This article will explain the consequences of putting coolant in windshield wiper fluid or putting windshield fluid in the coolant. Most importantly, you’ll learn what to do when you accidentally put wiper fluid in coolant.

Accidentally Put Windshield Fluid in Coolant

What will Happen If you accidentally put windshield fluid in the coolant?

Before looking at what will happen when you pour windshield fluid in coolant, let’s see where you should pour the windshield fluid.

The windshield wiper is sprayed on the windshield when you turn the wiper knob. The fluid has different formulations; some are pre-mixed, while others are not. The non-pre-mixed fluid requires dilution before using them. They are typically labeled “De-icer,” “Bug remover,” or “All season,” and they generally are a mixture of water, detergent, and solvent.

The detergent and solvent used in formulating the windshield fluid help clean dirt on the windshields. In contrast, the engine coolant is a mixture of water and antifreeze. The antifreeze is formulated with ethylene glycol, which helps in regulating optimal engine temperature. In other words, ethylene glycol helps prevent the water in the coolant from evaporating, boiling, or freezing.

From the above explanation, you have seen that the windshield wiper fluid and the engine coolant are formulated with different compounds that do different functions. So if you are asking, is coolant the same as windshield washer fluid? The simple answer is no. But in reality, will accidentally adding a windshield or de-icer in coolant reservoir cause any harm?

Don’t panic if you accidentally put windshield wiper fluid in coolant because it won’t cause any harm to the engine. However, don’t let the windshield fluid sit in the coolant; flush the cooling system to ensure you removed all the fluid, then refill the coolant reservoir with the recommended engine coolant.

Putting windshield fluid in the radiator or coolant reservoir is not harmful and is not a good practice. Other chemical compounds used in formulating the wiper fluid will not stop the antifreeze in the radiator from doing its job.

However, pouring wiper fluid into the engine coolant on purpose or ignoring it even when you accidentally pour it can cause the radiator and the cooling lines to clog up. Remember I explained that the wiper fluid contains detergent and solvents? These detergents and solvents will easily expand when the engine heats up.

If the windshield is left in the coolant for an extended period, some of the chemicals used in formulating it will react with the coolant and form a gel-like substance.

Lastly, some wiper fluids contain alcohol. If such fluid is added to the engine coolant, as the engine heats up, the alcohol will boil and escape through the radiator cap or the reservoir cover. This will lead to a loss of engine coolant. Plus, alcohol introduced into the coolant will affect gaskets, seals, and hoses.

accidentally poured windshield wiper fluid in coolant

What to do if you put windshield fluid in the coolant?

So what should you do if you have accidentally poured windshield fluid into the coolant reservoir or radiator? Leaving the wiper fluid in the coolant for an extended period will cause several issues. So, the best solution is to drain all the fluid.

Drain all the fluid in the cooling system and refill with a 50/50 coolant as recommended by your owner’s booklet. However, if you have driven the vehicle, flush out the entire coolant to remove all the windshield fluid in the car and refill the coolant as needed.

Truth be told, there’s no major or real effect to your engine for adding wiper fluid to the engine coolant as far as you drain out the washer fluid and pour in the recommended fluid. It is just like when you accidentally put water in coolant. You only need to drain the fluid and pour in the recommended one. Now you are okay. Just remove the fluid immediately and put the specified coolant in your vehicle. 

Frequently Asked Questions (FAQs)

Can you mix windshield washer fluid with antifreeze?

While the major compound in windshield fluid is water, do not mix them. If you accidentally do, drain the fluid immediately and pour in the recommended fluid. However, there’s no short-term effect, but over time, the mixture will cause severe issues.

How do you get coolant out of a windshield washer reservoir?

If you are wondering, I accidentally put 4 ounces of windshield washer fluid in my antifreeze reservoir; how do I get it out?  

The best way to get coolant out of the windshield washer reservoir is to disconnect the down hoses connected to the reservoir and let the coolant pour out. After that, pour in the recommended washer fluid. Meanwhile, remember to place the catch pan underneath the reservoir to catch the coolant. If not, you’ll mess up the entire area.

Is windshield washer fluid the same as coolant?

No, coolant/antifreeze and windshield washer fluid are not the same. The washer fluid improves visibility in stormy and rainy weather by melting ice and cleaning the windshield. Coolant, on the other hand, keeps the engine from overheating in summer and freezing in winter.

Is washer fluid corrosive?

Windshield washer fluid contains several chemicals, one of which is alcohol. The alcohol in it makes it corrosive, especially to your car paint. So if you mistakenly pour windshield washer fluid on your paintwork, wash off the affected area with clean water immediately and dry it with a clean rag.

Final Words

If you have been reading to this point, you’ll no longer ask what happens when you accidentally put windshield fluid in coolant reservoir.

To be precise, if you accidentally put windshield washer fluid in a coolant reservoir, it won’t cause any harm provided you flush it out. If you have not driven the vehicle, you only need to drain it, but if you have driven it, you must flush the coolant.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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