2003 GMC Envoy Owner's Manual - Page 332

Windshield Washer Fluid What to Use When you need windshield washer fluid, sure to read be the manufacturer's instructionsbefore use. If you will be operating your vehicle in an area where the temperature may fall below freezing, use fluid that has sufficient a protection against freezing.See Engine Compartment Overview on page 5-12for reservoir location. Notice: 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 parts of the washer system.Also, water doesn't clean as well as washer fluid. Adding Washer Fluid Open the cap with the washer symbol on it. Add washer fluid until the tank is full. Fill your washer fluid tank only three-quarters full when it's very cold. This allows for expansion if freezing occurs, which could damage the tank ifit is completely full. Don't use engine coolant (antifreeze) in your windshield washer. It can damage your washer system and paint. W 5-37