Tired of streaks and marks on your vehicle?s windshield? Rain-X Windshield Washer Fluid Additive makes it look brand new. It?s simple. Add Rain-X Washer Fluid Additive to water and let your windshield wipers do all of the hard work. Just four ounces is enough to treat an entire gallon of water. Not only will your car look its best, but you?ll feel better as you enjoy increased visibility while you drive, improving safety for you and all of your passengers.