GMC 1996 Sonoma Owner's Manual page 201

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 SO/SO mixture of clecr/z cr.nter-
(preferably distilled) and DEX-COOL
TM
(orange-colored,
silicate-free) antifreeze at the coolant recovery tank. (See
"Engine Coolant" in the Index for more information.)
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like alcohol, can boil before the proper
coolant mix will. Your vehicle's coolant warning
system is set for the proper coolant mix. With
plain water or the wrong mix, your engine could
get too hot but you wouldn't get the overheat
warning. Your engine could catch fire and you or
others could be burned. Use a
50/50
mix of clean
water and DEX-COOL
TM
antifreeze.
NOTICE:
In cold weather, water can freeze and crack the
engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mix.
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