Cadillac CT6 2017 Owner's Manual page 258

Caution
If improper coolant mixture,
inhibitors, or additives are used in
the vehicle cooling system, the
engine could overheat and be
damaged. Too much water in the
mixture can freeze and crack engine
cooling parts. The repairs would not
be covered by the vehicle warranty.
Use only the proper mixture of
engine coolant for the cooling
system. See Recommended Fluids
and Lubricants 0 318.
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.
3.0L V6 Engine Coolant Surge Tank
3.6L V6 Engine Coolant Surge Tank
Check to see if coolant is visible in the
coolant surge tank. If the coolant
inside the coolant surge tank is
VEHICLE CARE
boiling, do not do anything else until
it cools down. If coolant is visible but
the coolant level mark is not visible,
add a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant at the coolant surge tank to
the top rib on the middle of the tank,
but be sure the cooling system is cool
before this is done. See Engine
Overheating 0 259.
The coolant surge tank is in the
engine compartment on the passenger
side of the vehicle. See Engine
Compartment Overview 0 247.
How to Add Coolant to the
Coolant Surge Tank
Caution
This vehicle has a specific coolant
fill procedure. Failure to follow this
procedure could cause the engine to
overheat and be severely damaged.
If no problem is found, check to see if
coolant is visible in the coolant surge
tank. If coolant is visible but the
coolant level is not at the indicated
level mark, add a 50/50 mixture of
257