GMC 2009 Sierra - Manual (Page 336)

What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL
® coolant which will not damage
aluminum parts. If you use this coolant mixture,
you do not need to add anything else.
{ 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
® coolant.
Notice: If you use an improper coolant mixture, your
engine could overheat and be badly damaged. The
repair cost would not be covered by your warranty.
Too much water in the mixture can freeze and crack
the engine, radiator, heater core, and other parts.
If you have to add coolant more than four times a year,
have your dealer/retailer check your cooling system.
Notice: If you use extra inhibitors and/or additives
in your vehicle’s cooling system, you could damage
your vehicle. Use only the proper mixture of the
engine coolant listed in this manual for the cooling
system. See Recommended Fluids and Lubricants
on page 6-12 for more information.
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