windshield washer fluid

October 7, 2006 12:23 AM

Windshield washer fluid vs. soap/detergent + water -- what's the difference?

Can I replace one with the other? Aside from the fact that it might be too sudsy...what problems might it cause?

posted by randomstriker to Travel & Transportation (16 answers total)

It'll probably freeze in cold weather.
posted by knave at 12:34 AM on October 7, 2006

washer fluid is alcohol based. it dries quickly. and it's like $1 a bottle. soap and water will smear the window and the wiper blades will not be able to squeegee the soap film off the window.
posted by cosmicbandito at 12:36 AM on October 7, 2006

Add some alcohol to that recipe to avoid freezing.

Googling reveals this recipe:

Ingredients:

* 3 cups rubbing alcohol
* 10 cups water
* 1 Tablespoon of liquid detergent

Makes one gallon.

Optional: You can add some blue food coloring if you like!
posted by empyrean at 12:37 AM on October 7, 2006

Commercial windshield washer fluids are typically 30-50% methanol, water, and perhaps a little detergent. Sometimes they contain a wetting agent that helps to minimize mineral deposits. If you choose to make your own, you might consider substituting distilled water for the water in your homemade recipe if your local water has a high mineral content. If you want to get your own methanol, a fairly easy way is buying the yellow bottle HEET brand gas line antifreeze - it's about 99% methanol. You can find it in auto parts stores.
posted by RichardP at 1:16 AM on October 7, 2006

Response by poster: soap and water will smear the window and the wiper blades will not be able to squeegee the soap film off the window

Then why can you squeegee it off with a squeegee?

So the alcohol is just to prevent freezing...unnecessary since I live in a locale where it rarely dips below freezing?
posted by randomstriker at 1:36 AM on October 7, 2006

While in California I ran out of washer fluid and got it refilled at a local gas station. They mixed up some liquid in a bucket with water and some special soap. It was real cheap and kept my windshield nice and clean. Then I drove back home to Ontario, and first snowstorm - frozen solid!

If you live in a warm climate you're fine. Just don't go driving up in the mountains in winter.
posted by PercussivePaul at 2:17 AM on October 7, 2006

Then why can you squeegee it off with a squeegee?
Because, with a handheld squeegee, you are exerting far more force on the blade (in order to remove the soapy film) than is ever exerted by your wiper blades.
posted by Thorzdad at 5:09 AM on October 7, 2006

Be careful that your choice of detergent doesn't remove wax. Many laundry and dishwashing formulations are designed to.
posted by Mitheral at 7:52 AM on October 7, 2006

So the alcohol is just to prevent freezing...unnecessary since I live in a locale where it rarely dips below freezing?

No, it'd be unnecessary in a locale where it never dips below freezing. Remember that the 60mph wind that your wet windshield is exposed to on the highway will make things a bit colder for your washer fluid too.
posted by mendel at 8:30 AM on October 7, 2006

Remember that the 60mph wind that your wet windshield is exposed to on the highway will make things a bit colder for your washer fluid too.

Not exactly. It will bring the temperature down faster, but it won't cool the fluid colder than ambient.
posted by Kwantsar at 8:52 AM on October 7, 2006

Kwantsar: yes it will! Evaporative cooling is how come humans are only 98.6 degrees even if the air is 102 degrees.
posted by aubilenon at 1:03 PM on October 7, 2006

Great. Now you can show me the sweat glands on the washer fluid reservoir.
posted by Kwantsar at 1:24 PM on October 7, 2006

Or you could take the NOAA's word for it.
posted by Kwantsar at 1:29 PM on October 7, 2006

I wouldn't mess with methanol. The Merck index says as little as 30ml (~1oz) has been fatal, that it can be absorbed through the skin or by breathing vapors (your car's air intake may be at the base of your windshield-- mine is), and that chronic exposure causes visual impairment.
posted by jamjam at 2:08 PM on October 7, 2006

Great. Now you can show me the sweat glands on the washer fluid reservoir.

I think what mendel is suggesting is that the fluid will freeze on the windshield, which is arguably more dangerous than having it freeze in the reservoir.
posted by Opposite George at 2:16 PM on October 7, 2006

Yeah, that's what I was suggesting. That happens about once a year to me, when it gets cold and I still have the "get the bugs off" summer fluid in instead of the "don't turn the windshield opaque" winter fluid in. It's even better when you're using the fluid to clear the window because of freezing rain and you end up just adding more freezing rain.
posted by mendel at 7:39 PM on October 7, 2006