1996 GMC Sonoma Owner's Manual - Page 252

Adding Washer Fluid NOTICE: 0 0 0 Open the cap labeled WASHER FLUID ONLY. Add washer fluid until the tank is full. 0 When using concentrated washer fluid, follow the manufacturer's instructions for adding water. Don't mix water with ready-to-use washer fluid. Water can cause the solution to freeze and damage your washer fluid tank and other partsof the washersystem. Also, water doesn't clean as well as washer fluid. Fill your washer fluid tank only 3/4 full when it's very cold. This allows for expansion, which could damage the tank if it is completely full. Don't use radiator antifreezein your windshield washer. It can damage your washer system and paint. 6-30