I found these tips on the following web site:
http://www.scgh.com/go-green/cleaning/homemade-windshield-washer-fluid-more-green-than-blue/
Winter driving in many parts of the United States is treacherous. Drivers must contend with freezing rain, ice, snow, slush, and road slop. All of these conditions add danger to running errands or commuting. A dirty, hazy, or road-slop-covered windshield or windscreen makes it even worse. It is an absolute must to have a clean windshield at all times, especially during the winter months.Homemade Windshield Washer Fluid: the Environmentally Friendly Alternative
A simple and environmentally friendly windshield washer fluid can be made using just a couple of household items. In a clean one-gallon plastic milk jug, mix one-half (1/2) to one (1) pints of isopropyl alcohol (rubbing alcohol) and one tablespoon of any liquid grease-removing dish detergent. Fill the jug with water, cap, and shake well.Now, place the mixture in your vehicle’s windshield washer fluid reservoir. Test your homemade and environmentally friendly windshield washer fluid mixture, as you usually operate your vehicle’s windshield washer system. You will see the clean!Isopropyl alcohol is a much safer alternative than methanol (methyl alcohol), which is in the “blue” commercial products. If you read most any commercial windshield washer fluid product labels, you will see a “hazard” warning. Methanol (methyl alcohol) is a hazardous chemical and should be used with caution.Another green and eco-friendly alternative is to use distilled white vinegar instead of isopropyl (rubbing) alcohol. However, if you choose to use vinegar, which is an old-school cleaner for nearly everything, it may freeze in the windshield washer fluid reservoir. So, a vinegar and water solution may be more suitable for warmer climates or warmer months in colder climates. Also, vinegar does have a characteristic odor that may not be desired.If you choose to use the vinegar and water solution, a mixture of between 1:1 and 3:1 parts vinegar to water and a small bit of liquid dish detergent. Do not use too much detergent because it may leave a residue on your windshield
