Combining water, vinegar and window cleaner creates a homemade substitute for windshield washer fluid. If the indicator light for low washer fluid levels come on in the car, people who don't have time to run out to the store and buy more fluid have access to a homemade solution.
The proper ratio of window cleaner to water is 3 cups to 1 gallon, although adjusting the ratio upward makes the cleaner a bit stronger. Adding too much window cleaner causes the system to form streaks on the window. Adding the vinegar keeps the mixture from freezing, which is important during colder weather. Eight ounces of vinegar is the right amount for 1 gallon of water.