1998 GMC Savana Van Owner's Manual - Page 266

What to Use To determine what kind of fluid to use, see "Recommended Fluids and Lubricants" in the Index. Always use the proper fluid. Failure to use the proper fluid can cause leaks and damage hoses and seals. Adding Washer Fluid Windshield WasherFluid 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. Open the cap labeled WASHER FLUID ONLY. Add washer fluid until the tank is full. 6-26