There is no standard freeze point for windshield washer fluid. Instead, the freeze point is determined by the concentration of methanol. This varies by manufacturer and is often listed on the label. Concentrated windshield washer fluid can be mixed in the dilution desired to achieve a given freeze point. For instance, one manufacturer list: ratio of concentrate to water Freeze point (Fahrenheit) 1 to 1 -49 degrees 1 to 2 -13 degrees 1 to 3 zero degrees 1 to 4 10 degrees 1 to 5 14 degrees 1 to 10 26 degrees Methanol is toxic and can be flammable. Concentrate should never be mixed in excess of the protection required.