Page 256 of 434

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 255
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels greater than 15% by
volume.
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 that 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,
ferrocene, and aniline.
These fuels can corrode
metal fuel system parts or
damage plastic and rubber
parts.
(Continued)
Caution (Continued)
.Fuel containing metals such
as methylcyclopentadienyl
manganese tricarbonyl
(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.
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 0255.
Fuel Additives
TOP TIER Detergent Gasoline is
highly recommended for use with
your vehicle. If your country does
not have TOP TIER Detergent
Gasoline, add ACDelco Fuel
System Treatment Plus−Gasoline to
the vehicle’ s gasoline fuel tank at
every oil change or 15 000 km
(9,000 mi), whichever occurs first.
TOP TIER Detergent Gasoline and
ACDelco Fuel System Treatment
Plus−Gasoline will help keep your
vehicle’s engine fuel deposit free
and performing optimally.
E85 or FlexFuel
Vehicles with a yellow fuel sticker
on the fuel door can use either
unleaded gasoline or fuel containing
up to 85% ethanol (E85). All other
vehicles should use only the
unleaded gasoline as described in
Recommended Fuel (L83 5.3L
V8 Engine) 0254 or
Recommended Fuel (L86 6.2L
V8 Engine) 0254.
Page 412 of 434

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
OnStar 411
Press=to:
. Open the OnStar app on the
infotainment display. See the
infotainment manual for
information on how to use the
OnStar app.
Or
. Give OnStar Turn-by-Turn
Navigation voice commands.
. Obtain and customize the Wi-Fi
hotspot name or SSID and
password, if equipped.
Press
Qto connect to an
Advisor to:
. Verify account information or
update contact information.
. Get driving directions.
. Receive a Diagnostic check of
the vehicle's key operating
systems.
. Receive Roadside Assistance.
. Manage Wi-Fi Settings,
if equipped. Press
>to get a priority connection
to an OnStar Advisor available 24/
7 to:
. Get help for an emergency.
. Be a Good Samaritan or
respond to an AMBER Alert.
. Get assistance in severe
weather or other crisis situations
and find evacuation routes.OnStar Services
Emergency
Emergency Services require an
active safety and security plan. With
Automatic Crash Response, built-in
sensors can automatically alert a
specially trained OnStar Advisor
who is immediately connected in to
the vehicle to help.
Press
>for a priority connection to
an OnStar Advisor who can contact
emergency service providers, direct
them to your exact location, and
relay important information.
With OnStar Crisis Assist, specially
trained Advisors are available
24 hours a day, 7 days a week, to
provide a central point of contact,
assistance, and information during a
crisis.
With Roadside Assistance, Advisors
can locate a nearby service provider
to help with a flat tire, a battery
jump, or an empty gas tank.
Page 426 of 434

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./Cana-
da/Mexico-13566587) - 2020 - CRC - 4/15/19
Index 425
Fluid (cont'd)Four-Wheel Drive
Transfer Case . . . . . . . . . . . . . . . 219
Washer . . . . . . . . . . . . . . . . . . . . . . . 302
Fog Lamps . . . . . . . . . . . . . . . . . . . . . 169 Bulb Replacement . . . . . . . . . . . . 312
Folding Mirrors . . . . . . . . . . . . . . . . . . 38
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . . 245
Four-Wheel Drive . . . . . . . . . . 219, 305
Four-Wheel-Drive Light . . . . . . . . . 139
Frequency Statement Radio . . . . . . . . . . . . . . . . . . . . . . . . . 405
Front Axle . . . . . . . . . . . . . . . . . . . . . . 306
Front Fog Lamp
Light . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Front Seats Heated and Ventilated . . . . . . . . . . 54
Fuel Additives . . . . . . . . . . . . . . . . . . . . . 255
Economy, Driving for Better . . . 184
Filling a Portable FuelContainer . . . . . . . . . . . . . . . . . . . 258
Filling the Tank . . . . . . . . . . . . . . . 256
Foreign Countries . . . . . . . . . . . . 255
Gauge . . . . . . . . . . . . . . . . . . . . . . . . 130
Low Fuel Warning Light . . . . . . . 142
Management, Active . . . . . . . . . . .211 Fuel (cont'd)
Prohibited Fuels . . . . . . . . . . . . . . 255
Recommended . . . . . . . . . . . . . . . 254
Top Tier . . . . . . . . . . . . . . . . . . . . . . 254
Full-Size Spare Tire . . . . . . . . . . . . 359
Fuses Engine Compartment FuseBlock . . . . . . . . . . . . . . . . . . . . . . . . 315
Fuses and Circuit Breakers . . . 315
Instrument Panel Fuse
Block . . . . . . . . . . . . . . . . . . . 320, 323
Rear Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 325
G
Garage Door Opener . . . . . . . . . . . 160Programming . . . . . . . . . . . . . . . . . 160
Gas Strut(s) . . . . . . . . . . . . . . . . . . . . 310
Gauges Engine CoolantTemperature . . . . . . . . . . . . . . . . 131
Engine Oil Pressure . . . . . . . . . . 130
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Odometer . . . . . . . . . . . . . . . . . . . . . 129
Speedometer . . . . . . . . . . . . . . . . . 129
Tachometer . . . . . . . . . . . . . . . . . . . 129
Transmission Temperature . . . . 132
Trip Odometer . . . . . . . . . . . . . . . . 129 Gauges (cont'd)
Voltmeter . . . . . . . . . . . . . . . . . . . . . 133
Warning Lights and
Indicators . . . . . . . . . . . . . . . . . . . 125
General Information Service and Maintenance . . . . . 377
Towing . . . . . . . . . . . . . . . . . . . . . . . . 259
Vehicle Care . . . . . . . . . . . . . . . . . . 282
Glass Replacement . . . . . . . . . . . . . 310
Glove Box . . . . . . . . . . . . . . . . . . . . . . 109
GM Mobility Reimbursement
Program . . . . . . . . . . . . . . . . . . . . . . . 399
H
Hazard Warning Flashers . . . . . . . 168
Head Restraints . . . . . . . . . . . . . . . . . 47
Head-up Display . . . . . . . . . . . . . . . . 147
HeadlampsAiming . . . . . . . . . . . . . . . . . . . . . . . . 312
Automatic . . . . . . . . . . . . . . . . . . . . . 167
Bulb Replacement . . . . . . . . . . . . 312
Daytime Running
Lamps (DRL) . . . . . . . . . . . . . . . . 167
Flash-to-Pass . . . . . . . . . . . . . . . . . 167
High Intensity Discharge
(HID) Lighting . . . . . . . . . . . . . . . 312
High-Beam On Light . . . . . . . . . . 143
High/Low Beam Changer . . . . . 166