H Beken, a 60 year old male from Dayton, Ohio asks on January 7, 2005,I have been trying to find formulas for simple auto windshield washer fluid. Can't find anything. What are the amounts of what to make it up? I'm getting tired of paying $ 2.50 per gallon. I'm thinking it's water and glycol alcohol based and maybe isopropanol. What would a good and cheaper way of making it be?
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Windshield washer fluid is indeed made of a mixture of water and alcohols to lower the freezing point. Available in most public libraries, the CRC Handbook of Chemistry and Physics, 56th edn, table D-237 gives freezing points of methanol-water mixtures, so a 1-methanol to 2-water, i.e. about 33% methanol has freezing point of -30C; 15% is about -10C. Table D-220 gives a variety of solute/solvent tables. But this won't likely solve your problem. I doubt you can beat the $2.50 per gallon price. [Editor: a quick google search gives a recipe of 3 cups Isopropyl alcohol, 2 teaspoons liquid detergent in 10 cups of water. You are likely to find that 3 cups of isopropyl alcohol costs more than $2.50, and it might not lower the freezing point of water as much as the commercial product. Best advice is to make the stuff last longer by diluting your gallon of $2.50 windshield washer liquid with water during periods of moderate freezing weather and certainly in summer. But when it's -40, you will need it full strength.]
It depends on the climate. If you live in a region where the temperature is below the freezing point you must have methanol in the washer fluid. In general you need 30 - 50% alcohol for a quantity of water. To this you can add a small amount of detergent. It would be better to test your mixture by leaving it in a container outside one night before putting it into your car. One possible warning: I have read that one of the alcohols (methanol or isopropanol?) can turn rubber white.
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