What is Windshield Washer Fluid?

Windshield washer fluid is a specially formulated mixture designed to clear away grime, bugs, and dirt from your car's windshield, ensuring clear visibility. It contains detergents, solvents, and sometimes antifreeze agents to perform effectively in various weather conditions. Curious about what makes it work so well, or why it's essential for safe driving? Let's delve deeper into the science behind it.
Christina Edwards
Christina Edwards

Windshield washer fluid is one of many fluids necessary for safe driving. Known as screen wash in the United Kingdom, windshield wiper fluid helps keep a vehicle's windshield clear from such things as dirt, road grime, bugs, and sometimes even frost. Being able to clearly see out the windshield is considered imperative to safe driving.

Depending on the type of fluid used, the liquid will often contain methanol. This is a type of alcohol that is very effective in cutting through thick grime and road tar, making it a very popular addition to many brands of wiper fluid. Ethylene glycol is another common ingredient in these automotive chemicals, especially in those that are meant to help remove frost and ice from a windshield. This chemical is also found in anti-freeze and is used to de-ice airplane wings and runways.

Ingestion of windshield washer fluid may result in sleepiness.
Ingestion of windshield washer fluid may result in sleepiness.

These main ingredients can be quite harmful if ingested by people or animals. If a small amount is ingested, it often simulates the effects of intoxication, causing staggering, sleepiness, and vomiting. Larger amounts could possibly cause blindness, coma, or even death.

Other less toxic ingredients in windshield washer fluid include dye and water. The dye is usually a bright blue color. Water often makes up nearly half of the fluid, except in the concentrated varieties.

Probably the most commonly known way to buy windshield washer fluid is pre-mixed in a gallon jug. Concentrated mixtures, however, can also be purchased. For the everyday consumer, concentrated washer fluid can be found at large chain stores or local automotive supply stores. Larger amounts, anywhere from 5 to 55 gallons (19 to 208 liters), are available for purchase by larger companies that would have a use for such a product, including garages and auto dealerships.

The windshield washer fluid in most vehicles is stored under the hood in a clearly marked reservoir. From there, it is pumped through tubes to a small nozzle or nozzles located just below the windshield, or sometimes on the wipers themselves. After the fluid is squirted or misted onto the windshield, the wipers are activated and clear the windshield. The pump is typically activated when an operator inside the vehicle pushes or pulls a switch, often located on the windshield wiper control. Many mechanics strongly advise against switching on the wipers without any moisture on the windshield, as this can damage the wiper blades, or possibly even scratch the windshield.

To help clear away frost and ice, some car manufacturers have begun producing vehicles that preheat the windshield washer fluid before it squirts onto the window. One of these car companies is General Motors (GM). In 2006, for example, GM began making this a standard feature in one of its Buick sedans. Shortly afterward, however, many of these features were recalled due to a possible fire hazard.

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Discussion Comments


Here's something I learned the hard way -- windshield washer fluid that is just fine here in the South might not be worth much in the winter in the North. I learned that when I was in Iowa one December and the high temperature during that week was eight degrees.

By the way, never tell someone in Iowa that it's cold.

"This isn't cold. I'll tell you about cold," they'll say before bragging about how cold it's been at some point. Strange.

At any rate, my windshield washer fluid froze into a solid, blue brick in those frigid temperatures -- something I didn't think was possible. That's a real problem when ice starts to melt, cars splash dirty water all over your windshield and you could really use some windshield wiper fluid that isn't frozen solid.

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    • Ingestion of windshield washer fluid may result in sleepiness.
      By: Andres Rodriguez
      Ingestion of windshield washer fluid may result in sleepiness.