GMC 1997 Safari Owner's Manual page 287

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.
Adding Washer Fluid
Open the cap labeled
WASHER FLUID ONLY.
Add washer fluid until the
tank is full.
NOTICE:
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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.
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 if it is
completely full.
Don't use radiator antifreeze in your
windshield washer. It can damage your
washer system and paint.