Pontiac 2006 GTO Owner's Manual page 221

How to Add Coolant to the Coolant
Overflow Reservoir
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CAUTION:
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil
before the proper coolant mixture will. Your
vehicle's coolant warning system is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you would not get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
If you have not found a problem yet, check the coolant
level on the coolant overflow reservoir dipstick. If
the coolant level is not at or above the bottom arrow on
the dipstick, add a 50/50 mixture of clean, drinkable
water and DEX-COOL
reservoir. See Engine Coolant on page 5-23 for
more information.
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 mixture.
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You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol
®
coolant. and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
®
coolant at the coolant overflow
CAUTION:
5-31