GMC 2012 Sierra Denali Owner's Manual page 356

10-18 Vehicle Care
Notice: If extra inhibitors and/or
additives are used in the vehicle
cooling system, the vehicle could
be damaged. Use only the proper
mixture of the engine coolant
listed in this manual for the
cooling system. See
Recommended Fluids and
Lubricants on page 11 12 for
more information.
Never dispose of engine coolant by
putting it in the trash, pouring it on
the ground, or into sewers, streams,
or bodies of water. Have the coolant
changed by an authorized service
center, familiar with legal
requirements regarding used
coolant disposal. This will help
protect the environment and your
health.
Checking Coolant
The vehicle must be on a level
surface when checking the coolant
level.
Check to see if coolant is visible in
the coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, do not do anything else until
it cools down. If coolant is visible
but the coolant level is not at or
above the FULL COLD mark, add a
50/50 mixture of clean, drinkable
water and DEX-COOL coolant at the
coolant surge tank, but be sure the
cooling system is cool before this
is done.
The coolant surge tank is located in
the engine compartment on the
passenger side of the vehicle. See
Engine Compartment Overview on
page 10 6 for more information on
location.
The coolant level should be at or
above the FULL COLD mark. If it is
not, the vehicle may have a leak in
the cooling system.