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Does Windshield Wiper Fluid Freeze? If So, How To Prevent?

Currently working on the windscreen washer.

Thankfully, windshield wiper fluid does not freeze. You’re driving down an icy road that hasn’t been scraped and sanded. The wipers almost can’t keep up with the snow falling on your windscreen. A big rig drives by, slinging slush all over your car and windscreen. All that muddy slush is leaving tracks on your windscreen.

You hit the windshield wiper fluid to clean it all up, thankful that it does and doesn’t come out as a solid block of ice. This happened to me once, so if it ever happens to you, make sure your reservoir is full of washer fluid. It could save your life one dark, snowy night. Have you ever wondered why it doesn’t freeze and how to keep it from happening?

It Can’t Be Too Bad If The Internet Tells Us How To Make Homemade Windshield Washer Fluid. Of What Is It Made?

Pouring antifreeze to clean the car's windshield.

Store-bought wiper fluid is made with ethanol and methanol, two highly toxic poisons that damage the environment and the paint on your car. They, along with antifreeze, cut through the mud, crud, pollen, bird droppings, and other dirt that get on your windscreen. Ordinary water can’t cut through all that, but these toxic ingredients can. 

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These chemicals won’t freeze until the weather reaches 20 to 50 degrees below zero. The snag to that is that when the methanol hits the air, it evaporates. Methanol is a mix of water and methyl alcohol. The mixture has to be cut with water due to the flammability of the chemicals.

If they weren’t cut with water, they’d never make it into your car. They’d explode. The detergents and solvents in these chemicals cut through the crap on your windscreen to leave it sparkling clean and streak-free. The little water that’s in the mix won’t freeze, at least until it gets out of the washer fluid reservoir. Then it’s on its own.

I Might Not Live In An Area Where The Temps Get To 30 Or More Below Zero, But I’d Still Like To Know How To Prevent My Fluid From Freezing

Background of an old, dusty window.

Look anywhere on the Internet, and they’ll tell you to add rubbing alcohol to windshield washer fluid to prevent it from freezing. They’ll also tell you to add anti-freeze. Let’s say, though, that you have neither on hand.

You look around the house and find your stash of vodka or gin. Grab it, because you’re going to winterize your windshield fluid with it. Lots of people put their liquor in the freezer to keep it cold, but they notice it never freezes.

That’s due to the freezer freezing foods at higher temperatures than it is outside. For instance, experts tell us that our food is safe when it’s cooled in the fridge at 35 degrees. The freezer is safe for our food at -18 degrees. 

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So adding your vodka, gin, rum, or other white liquor to your windshield cleaning mixture will help not only winterize the fluid but it will cut through the crud on your windscreen. 

I Just Want To Know Why My Washer Fluid Froze. It Isn’t Even That Cold Outside.

Hybrid wiper blades are used on dirty car glass, and the washer sprays water over the windshield.

The answer to that question is a two-parter. The first part involves a bit of physics, so grab a coffee and let’s go back to school for a minute. The cleaning mixture leaves the reservoir and travels through a tiny hose to deliver the mixture to your windscreen.

Once it leaves the hose, the methanol or methyl alcohol evaporates. This leaves only water on your windscreen. What happens to water when it hits cold air? Yep, it freezes.

Now you have not only crud on your windscreen but ice from the frozen water. You should find a warm place to park where the windshield can get warm enough for the ice to melt and you can scrape it off. Keeping the windscreen warm allows the water to hit it and maintain its temperature range. 

The second part of the answer is about the seasons. In spring, summer, and fall, de-icer isn’t necessary in our windshield fluid. Summer fluid is usually pink or sometimes yellow in color and contains chemicals like ammonia and soaps like dishwashing liquid.

The idea behind summer fluid is to cut through the dead bugs, pollen, and other crud-like dirt and dust. There’s no need for heavy chemicals like anti-freeze and poisonous alcohols. The trouble comes with that first hard freeze.

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It always, but always, catches you unawares. You don’t remember to bring in the plants, and they look so pitiful the next morning. You forget to cover the outside spigots, and the kids get a kick out of seeing the ice hanging from them. 

Uh-oh. What about the windshield washer fluid? While a good heavy frost isn’t enough to freeze the fluid, it’s a heads-up that some maintenance needs to be done before it does freeze. You have to change the summer fluid out for winter fluid. Not only that, but you have to flush the lines leading from the reservoir to the outside of the car.

Remember to warm up the car so that the windscreen is warm when you test the fluid. When the alcohol evaporates, the water will hit the warm glass and not freeze.

What Happens To My Car If My Windshield Washer Fluid Freezes?

Tractor vehicle with an externally mounted washer fluid reservoir.

You can buy the fluid advertised as not freezing to 30 below up to 70 below, but once the ethylene glycol and methanol evaporate, you have a problem. The first thing that happens is the water freezes both in the reservoir and in the lines. Now the frozen reservoir cracks as the water expand in the freezing process.

The next thing is the pump becomes damaged. With a broken pump and a basically exploded reservoir, you aren’t getting any fluid to your now cruddy windshield.

The reservoir, pump, and possibly the lines will need replacement. Get your car safely to the mechanic and don’t even think of trying to drive until all this is fixed.

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Is There Anything Else I Should Know About Windshield Washing Fluid Freeze Prevention? How About Making My Own?

Shot of a wet car's windscreen and wipers up close.

Drivers without access to warm garages, engine block heaters, or heaters to keep the fluid reservoirs warm have recourse to other methods of freeze prevention. I, personally, consider homemade windshield cleaning solutions better for the environment and your car’s paint job.

I’m not fond of chemicals in any shape or form, so I use natural ingredients in everything from shampoo to car cleaning solutions. Gather these things to make your homemade fluid: a one-gallon jug, funnel, rubbing alcohol, white wine vinegar, and distilled and only distilled water.

This is due to leaving no residue whatsoever, so it’s best for your windscreen.  Now, mix three cups of distilled water, one cup of white wine vinegar, and one cup of rubbing alcohol. Pour the mixture into the gallon jug. 

Now, this is very important: leave the jug of mixture outside overnight. If it freezes, thaw it out and add one more cup of alcohol. Leave it out a second night. If it freezes again, add one more cup of alcohol and leave it out again.

Alcohol doesn’t freeze at the temperatures your area is likely to get, so keep adding alcohol until the water ratio is so low the mixture won’t freeze. Now you can put it in your car.

Does Windshield Wiper Fluid Freeze FAQs

Will My Windshield Wiper Fluid Freeze?

Woman filling unclean automobile with antifreeze screen wash from blue antifreeze water bottle.

Not necessarily. Commercially prepared wiper fluids are calibrated to work up to 50 degrees below zero. This should work in almost any city in the U. S. and possibly even Alaska. In the unlikely event that it does freeze, add alcohol or anti-freeze to the mix to help it remain unfrozen.

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How Shall I Prevent The Fluid From Freezing?

Keeping the glass as well as the fluid reservoir warm is the key to preventing fluid freezing. If this isn’t possible, add elements to the mix that don’t freeze, like rubbing alcohol, vodka or white rum, or anti-freeze. Keep the water ratio even with the additions due to the fire hazard of some of the chemicals.

How Does The De-Icer In My Windshield Fluid Work?

De-icer is a chemical that reacts with the ice on your windscreen. It decreases the melting point of the ice, thus morphing it into liquid. Your wipers then wipe it away.

I’m Standing In The Auto Supplies Shop. There Are Hundreds Of Bottles Of Windshield Cleaning Fluid. Which Do I Choose?

Woman pours fluid for cleaning windshields.

You have to know the climate in which you live before choosing things that deal with it. Research how low your temperatures go in winter. Then choose a windshield cleaning fluid that goes down to or surpasses that winter temperature, and you should be safe. If you don’t know, just ask the manager, who knows these things.

How Many Bottles Of Windshield Washing Fluid Will I Need?

They only come in gallon jugs, and most reservoirs are about three-quarters to one gallon. One bottle should do it with one as a backup. The reservoir is labeled with lines as a guide to tell you how much you’re putting in it. 

How Often Should I Replace The Fluid In The Windshield Cleaner Reservoir?

Your oil is changed regularly due to its circulation through the moving parts of your car’s engine. It becomes dirty and needs changing frequently. Windshield fluid isn’t like that because it doesn’t become dirty.

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Keep an eye on it, though. If the reservoir is empty and you need a clean windshield, both the motor and your windshield are in trouble. Pop the hood and check the level, adding more fluid as necessary.