Cadillac 2012 CTS Owner's Manual page 331

Adding only plain water or some
other liquid to the cooling system
can be dangerous. Plain water
and other liquids, can boil before
the proper coolant mixture will.
The coolant warning system is set
for the proper coolant mixture.
With plain water or the wrong
mixture, the engine could get too
hot but you would not get the
overheat warning. The engine
could catch fire and you or
others could be burned. Use a
50/50 mixture of clean, drinkable
water and DEX-COOL coolant.
Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant. If using this mixture,
nothing else needs to be added.
This mixture:
Gives freezing protection down
to 37°C ( 34°F), outside
temperature.
Gives boiling protection up to
129°C (265°F), engine
temperature.
Protects against rust and
corrosion.
Will not damage aluminum parts.
Helps keep the proper engine
temperature.
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.
The vehicle must be on a level
surface when checking the coolant
level.
The engine coolant reservoir is
located in the engine compartment
on the driver side of the vehicle.
See
.
Check to see if coolant is visible in
the surge tank. If the coolant inside
the 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.