2018 CADILLAC CT6 fuel

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
220 DRIVING AND OPERATING
the vehicle is ready to be driven. This
could take up to 15 seconds at
extremely cold temperatures. See
Vehicle Ready Light (PLUG-IN Only)
0151.
PLUG-IN Operation
This vehicle combines gasoline and
electric propulsion. The gasoline
engine will automatically start to
provide power and then shut off to
save fuel.
The engine may remain
running when:
.
Accelerating aggressively or
climbing hills.
. Vehicle speed is greater than
125 km/h (75 mph).
. Charging the high voltage battery.
. The heater is being used.
The engine and transmission work
together to provide propulsion power
at the highest efficiency. This may
result in higher engine speeds.
Stop/Start System
{Warning
Exiting the vehicle without first
shifting into P (Park) may cause the
vehicle to move. You or others may
be injured. Because the vehicle may
have an auto engine stop/start
feature, the vehicle's engine might
seem to be shut off; however, once
the brake pedal is released, the
engine will start up again.
Shift to P (Park) and turn the
ignition off before exiting the
vehicle.
The vehicle has a fuel saving stop/
start system to shut off the engine
and help conserve fuel.
Auto Engine Stop/Start
When the brakes are applied and the
vehicle is at a complete stop, the
engine may turn off. When stopped,
the tachometer may display Auto
Stop, or the Auto Stop light may come
on in the instrument cluster.
See Tachometer 0134 and Auto Stop Mode (Uplevel Cluster)
0150. When the
brake pedal is released or the
accelerator pedal is pressed, the
engine may restart.
Auto Stop may be deactivated if:
. A minimum vehicle speed is not
reached.
. The engine or transmission is not
at the required operating
temperature.
. The outside temperature is not in
the required operating range,
typically between -10 °C (14 °F)
and 50 °C (122 °F).
. The shift lever is in any gear other
than D (Drive).
. The battery has been recently
disconnected.
. The battery charge is low.
. The interior comfort level has not
reached the required level for the
climate control system or defog
settings.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
222 DRIVING AND OPERATING
too much gasoline. Try pushing
the accelerator pedal all the way
to the floor and holding it there
as you press ENGINE START/
STOP. Wait at least 15 seconds
between each try, to allow the
cranking motor to cool down.
When the engine starts, release
the accelerator. If the vehicle
starts briefly but then stops
again, do the same thing. This
clears the extra gasoline from the
engine. Do not race the engine
immediately after starting it.
Operate the engine and
transmission gently until the oil
warms up and lubricates all
moving parts.
Stop/Start System
{Warning
Exiting the vehicle without first
shifting into P (Park) may cause the
vehicle to move. You or others may
be injured. Because the vehicle may
have an auto engine stop/start
feature, the vehicle's engine might(Continued)
Warning (Continued)
seem to be shut off; however, once
the brake pedal is released, the
engine will start up again.
Shift to P (Park) and turn the
ignition off before exiting the
vehicle.
The vehicle has a fuel saving stop/
start system to shut off the engine
and help conserve fuel.
Auto Engine Stop/Start
When the brakes are applied and the
vehicle is at a complete stop, the
engine may turn off. When stopped,
the tachometer may display Auto
Stop, or the Auto Stop light may come
on in the instrument cluster.
See Tachometer 0134 and Auto Stop
Mode (Uplevel Cluster) 0150. When the
brake pedal is released or the
accelerator pedal is pressed, the
engine may restart.
Auto Stop may be deactivated if:
. A minimum vehicle speed is not
reached. .
The engine or transmission is not
at the required operating
temperature.
. The outside temperature is not in
the required operating range,
typically between -10 °C (14 °F)
and 50 °C (122 °F).
. The shift lever is in any gear other
than D (Drive).
. The battery has been recently
disconnected.
. The battery charge is low.
. The interior comfort level has not
reached the required level for the
climate control system or defog
settings.
See Automatic Climate Control
System (Quad Zone - Gasoline Only)
0 197 orAutomatic Climate Control
System (Dual Zone - Gasoline and
PLUG-IN) 0191.
. The Auto Stop time is greater than
two minutes.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
DRIVING AND OPERATING 223
The automatic engine stop/start
function can be disabled by
touching
hon the center stack.
When
hcomes on green in the
instrument cluster, the system is
active. The system is not active when
it comes on white with a slash
through it.
Engine Heater
Vehicles with the engine heater can
use this option in cold weather
conditions at or below −18 °C (0 °F) for
easier starting and better fuel
economy during engine warm-up. Plug
in the coolant heater at least four hours before starting your vehicle. An
internal thermostat in the plug-end of
the cord may exist which will prevent
engine heater operation at
temperatures above
−18 °C (0 °F).
{Warning
Do not plug in the engine block
heater while the vehicle is parked in
a garage or under a carport.
Property damage or personal injury
may result. Always park the vehicle
in a clear open area away from
buildings or structures.
To Use the Engine Heater
1. Turn off the engine.
2. Open the hood and unwrap the
electrical cord. The cord is
clipped to the diagonal brace on
the passenger side of the engine
compartment.
Check the heater cord for
damage. If it is damaged, do not
use it. See your dealer for a
replacement. Inspect the cord for
damage yearly. 3. Plug it into a normal, grounded
110-volt AC outlet.
{Warning
Improper use of the heater cord or
an extension cord can damage the
cord and may result in overheating
and fire.
. Plug the cord into a
three-prong electrical utility
receptacle that is protected by
a ground fault detection
function. An ungrounded
outlet could cause an electric
shock.
. Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension cord
in good operating condition,
or using a damaged heater or
extension cord, could make it
(Continued)

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
DRIVING AND OPERATING 227
SportMode
Sport Mode provides more responsive
acceleration than Tour Mode, but can
reduce efficiency. Use Tour Mode
whenever possible.
During some conditions, certain drive
modes may be unavailable. The
unavailable mode is grayed out in the
DIC menu and cannot be selected.
If in Sport or Hold Mode, the mode
may become unavailable and the
vehicle will return to Tour Mode. The
indicator light goes off and a DIC
message displays.
Press MODE to select Sport Mode. Press MODE again to return to Tour
Mode and it becomes active after
three seconds.
Hold
Mode
Use Hold Mode on a trip where it is
expected that all of the electric charge
will be depleted. Use Hold Mode
mainly during highway or high speed
driving to maximize both PLUG-IN
propulsion miles and fuel efficiency.
This mode places the remaining
battery charge into a reserve for the
driver to use as desired. Selecting this
mode transitions the vehicle to
gasoline propulsion to maintain the battery charge reserve. The reserve
battery charge will appear grayed out
while in this mode.
Upon exiting Hold Mode, the reserved
battery charge becomes available
again and the vehicle returns to
PLUG-IN propulsion.
Hold Mode will not change normal
vehicle acceleration or braking
performance.
Press MODE to select Hold Mode.
Press MODE again to return to Tour
Mode and it becomes active after
three seconds.
Out of Fuel/Engine
Unavailable
If the vehicle runs out of fuel, or the
engine will not start due to a
malfunction, the vehicle can continue
to be driven with electric propulsion
until the current charge is depleted.
The vehicle will have less responsive
acceleration. DIC messages indicate
reduced propulsion power, that the
engine is not available, and the need
for fuel or service.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
228 DRIVING AND OPERATING
Once the vehicle is refueled, or the
malfunction is corrected, the engine
will start the next time the vehicle is
turned on to perform a self test, and
DIC messages will not be displayed.
Once the engine starts successfully,
normal operation will continue with
either electric propulsion or with the
engine running. The engine will stop
running after the self test is
completed, and based on the current
mode of operation.
Maintenance Modes
Engine Maintenance Mode (EMM)
EMM runs the engine to keep it in
good working condition after
approximately six weeks of no or very
limited engine operation. EMM will
force the engine to run, even if there
is a charge to power the vehicle.
When EMM is needed, the EMM
Request screen appears on the
infotainment display at vehicle start.
If Yes is selected, EMM will begin. The
engine will not start until after a short
delay once shifted into D (Drive). The
engine will run for a set amount of
time without turning off. During
EMM, a DIC message displays to show
the EMM percentage complete.
If No is selected, the EMM Request
screen will appear when the vehicle is
next started. The EMM request can be
delayed for up to one day.
If the EMM request was delayed for
one day, EMM will automatically start
the engine at the next vehicle start.
The engine will not start until after a
short delay once shifted into D (Drive).An EMM Notification screen will
appear in the infotainment display.
If the vehicle is shut off during EMM,
it will restart the next time the vehicle
is driven.
A message displays to indicate that
EMM is active.
If EMM is required and the fuel level
is low, EMM may eventually empty
the fuel tank if fuel is not added. This

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
DRIVING AND OPERATING 229
will result in reduced, or no power. An
adequate fuel level must be
maintained in the vehicle to keep it
operational.
Fuel Maintenance Mode (FMM)
FMM tracks average fuel age. Old fuel
can cause engine problems. If low
engine usage causes average fuel age
to exceed approximately one year,
FMM will run the engine to use up
the old fuel. The engine will run until
enough fresh fuel is added to bring
the average fuel age into an
acceptable range. Allowing more old
fuel to be used up by FMM and
adding a larger amount of fresh fuel
will maximize the length of time
before another fuel maintenance
mode is needed. During FMM the
engine may turn on and off.
When FMM is needed, the FMM
Request screen appears on the
infotainment display at vehicle start.
If Yes is selected, FMM will begin. The
engine will not start until after a short
delay once shifted into D (Drive). FMM
will automatically continue at each
vehicle start until fresh fuel is added.
If No is selected, the FMM Request
screen will appear when the vehicle is
next started. The FMM request can be
delayed for only one day.If the FMM request was delayed for
one day, FMM will start at the next
vehicle start and display the FMM
Notification screen on the
infotainment display. The engine will
not start until after a short delay once
shifted into D (Drive).
If FMM is required and the fuel level
is low, FMM may eventually empty
the fuel tank if fuel is not added. This
will result in reduced, or no power. An
adequate fuel level must be
maintained in the vehicle to keep it
operational. After FMM has run it is
recommended to fill the fuel tank.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
286 DRIVING AND OPERATING
The following are the minimum
requirements for circuits used to
charge this vehicle:
.120 volts/15 amps
. 240 volts/20 amps
Charging equipment with a rating of
at least 240 volts/20 amps will provide
the fastest charging time and best
charging efficiency to recharge the
high voltage battery. 240 volt/40 amp
circuits provide flexibility for future
vehicle charging needs. Always follow
the charging equipment installation
instructions. Contact your dealer for
more information.
Caution
Do not use portable or stationary
backup generating equipment to
charge the vehicle. This may cause
damage to the vehicle's charging
system. Only charge the vehicle
from utility supplied power.
Fuel
GM recommends the use of TOP
TIER®detergent gasoline to keep the
engine cleaner and reduce engine
deposits. See www.toptiergas.com for a
list of TOP TIER detergent gasoline
marketers and applicable countries.
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels greater than 15% by
volume.
For the 2.0L L4 turbo engine,
premium unleaded gasoline meeting
ASTM specification D4814 with a
posted octane rating of 93 is highly
recommended for best performance and fuel economy. Unleaded gasoline
with an octane rated as low as 87 can
be used. Using unleaded gasoline
rated below 93 octane, however, will
lead to reduced acceleration and fuel
economy. If knocking occurs, use a
gasoline rated at 93 octane as soon as
possible, otherwise, the engine could
be damaged. If heavy knocking is
heard when using gasoline with a
93 octane rating, the engine needs
service.
For the 3.6L V6 engine, use regular
unleaded gasoline meeting ASTM
specification D4814 with a posted
octane rating of 87 or higher. Do not
use gasoline with a posted octane
rating of less than 87, as this may
cause engine knock and will lower fuel
economy.
For the 3.0L twin turbo V6 engine, use
premium unleaded gasoline meeting
ASTM specification D4814 with a
posted octane rating of 93.
If unavailable, unleaded gasoline with
a posted octane rating of 91 may be
used, but with reduced performance
and fuel economy. If the octane is less
than 91, the engine could be damaged
and the repairs would not be covered

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/14/17
DRIVING AND OPERATING 287
by the vehicle warranty. If heavy
knocking is heard when using gasoline
rated at 93 octane, the engine needs
service.
Prohibited Fuels
Caution
Do not use fuels with any of the
following conditions; doing so may
damage the vehicle and void its
warranty:. For vehicles which are not
FlexFuel, fuel labeled greater
than 15% ethanol by volume,
such as mid-level ethanol
blends (16 –50% ethanol),
E85, or FlexFuel.
. Fuel with any amount of
methanol, methylal, and
aniline. These fuels can
corrode metal fuel system
parts or damage plastic and
rubber parts.
. Fuel containing metals such
as methylcyclopentadienyl
manganese tricarbonyl
(Continued)
Caution (Continued)
(MMT), which can damage
the emissions control system
and spark plugs.
. Fuel with a posted octane
rating of less than the
recommended fuel. Using this
fuel will lower fuel economy
and performance, and may
decrease the life of the
emissions catalyst.
California Fuel
Requirements
If the vehicle is certified to meet
California Emissions Standards, it is
designed to operate on fuels that meet
California specifications. See the
underhood emission control label.
If this fuel is not available in states
adopting California Emissions
Standards, the vehicle will operate
satisfactorily on fuels meeting federal
specifications, but emission control
system performance may be affected.
The malfunction indicator lamp could
turn on and the vehicle may not pass a smog-check test. See
Malfunction
Indicator Lamp (Check Engine Light)
0 143. If this occurs, return to your
authorized dealer for diagnosis. If it is
determined that the condition is
caused by the type of fuel used,
repairs may not be covered by the
vehicle warranty.
Fuels in Foreign Countries
The U.S., Canada, and Mexico post
fuel octane ratings in anti-knock index
(AKI). For fuel not to use in a foreign
country, see “Prohibited Fuels” inFuel
0 286.
Fuel Additives
To keep fuel systems clean, TOP TIER
detergent gasoline is recommended.
See Fuel 0286.
If TOP TIER detergent gasoline is not
available, one bottle of GM Fuel
System Treatment Cleaner added to
the fuel tank at every engine oil
change, can help. GM Fuel System
Treatment Cleaner is the only gasoline
additive recommended by General
Motors. It is available at your dealer.