2003 GMC Sierra 1500 Pickup Owner's Manual - Page 421

Windshield Washer Fluid What to Use When you need windshield washer fluid, be sure to read the manufacturer's instructions before use. If you will be operating your vehicle in an area where the temperature may fall below freezing, use a fluid that has sufficient protection against freezing. See Engine Compartment Overview on page 5-12 for reservoir location. Notice: e 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 freeze and to damage yourwasher fluid tank and other parts of the washer system. Also, water doesn't cleanas well as washer fluid. Adding Washer Fluid Open the cap with the washer symbol on it. Add washer fluid until the tank is full. e Fill your washer fluid tank only three-quarters when it's very cold. This allows for expansion if freezing occurs, which could damage the tank if it is completely full. Don't use engine coolant (antifreeze) in your windshield washer. It can damageyour washer system and paint. Q 5-46