GMC 1995 Safari Owner's Manual page 186

How to Add Coolant to the Coolant Recovery Tank
If you haven't found a problem yet, but the coolant level isn't at ADD , add
a 50/50 mixture of clean water (preferably distilled) and a proper antifreeze
at the coolant recovery tank. (See "Engine Coolant" in the Index for more
information about the proper coolant mix.)
NOTICE:
In cold weather, water can freeze and crack the engine, radiator,
heater core and other parts. Use the recommended coolant.
When the coolant in the coolant recovery tank is at ADD
,
start your
vehicle.
If the overheat warning continues, there's one more thing you can try. You
can add the proper coolant mix directly to the radiator, but be sure the
cooling system is cool before you do it.
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