Add entire contents to washer fluid reservoir.  Fill reservoir to capacity with washer fluid or water.  Product will "splash" mix with washer fluid. 2)  For best results, start car and turn on defroster.  Spray washer fluid as needed until windshield is clear. A precise blend of ice-melting alcohols ensures premium performance at even very low temperatures and helps prevent dangerous re-freeze from forming on windshields. Prestones Dirt Blocker technology coats windshields with a resilient organo-modified siloxane copolymer.  This formulation imparts a durable hydrophobic surface on the windshield that helps prevent road spray from adhering to windshield glass by moving dirt particles away from the windshield surface and into the washe...  (less)