Cadillac 2010 CTS Sport Sedan Owner's Manual page 319

Adding only plain water to
the cooling system can be
dangerous. Plain water, or some
other liquid such as alcohol, can
boil before the proper coolant
mixture will. The vehicle's 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.
®
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.
See
for more information.