octane GMC SIERRA 1500 2011 Owners Manual

Black plate (84,1)GMC Sierra Owner Manual - 2011
9-84 Driving and Operating
Fuel
For diesel engine vehicles, see
“Fuel for Diesel Engines”in the
Duramax Diesel Supplement.
For Vehicles with gasoline engines,
please read this.
Gasoline
Use of the recommended fuel
is an important part of the proper
maintenance of this vehicle. To help
keep the engine clean and maintain
optimum vehicle performance, we
recommend the use of gasoline
advertised as TOP TIER Detergent
Gasoline.
Look for the TOP TIER label on the
fuel pump to ensure gasoline meets
enhanced detergency standards
developed by auto companies. A list
of marketers providing TOP TIER
Detergent Gasoline can be found
at www.toptiergas.com.
The eighth digit of the Vehicle
Identification Number (VIN) shows
the code letter or number that
identifies the vehicle's engine.
The VIN is at the top left of the
instrument panel. See Vehicle
Identification Number (VIN) on
page 12‑1.
Vehicles that have a FlexFuel badge
and a yellow fuel cap can use either
unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85). See
Fuel E85 (85% Ethanol) on
page 9‑87. For all other vehicles,
use only the unleaded gasoline
described under Recommended
Fuel on page 9‑84.
Recommended Fuel
For all vehicles except those with
the 6.2L V8 engine (VIN Code 2),
use regular unleaded gasoline
with a posted octane rating of 87 or
higher. If the octane rating is less
than 87, an audible knocking noise,
commonly referred to as spark
knock, might be heard when driving.
If this occurs, use a gasoline rated
at 87 octane or higher as soon
as possible. If heavy knocking is
heard when using gasoline rated
at 87 octane or higher, the engine
needs service.

Black plate (85,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-85
If the vehicle has the 6.2L V8 engine
(VIN Code 2), use premium
unleaded gasoline with a posted
octane rating of 91 or higher.
You can also use regular unleaded
gasoline rated at 87 octane or
higher, but the vehicle's acceleration
could be slightly reduced, and
a slight audible knocking noise,
commonly referred to as spark
knock, might be heard. If the octane
is less than 87, you might notice
a heavy knocking noise when you
drive. If this occurs, use a gasoline
rated at 87 octane or higher as soon
as possible. Otherwise, you could
damage the engine. If heavy
knocking is heard when using
gasoline rated at 87 octane or
higher, the engine needs service.Gasoline Specifications
(U.S. and Canada Only)
At a minimum, gasoline should
meet ASTM specification
D 4814 in the United States
or CAN/CGSB‐3.5 or 3.511 in
Canada. Some gasolines contain
an octane-enhancing additive called
methylcyclopentadienyl manganese
tricarbonyl (MMT). We recommend
against the use of gasolines
containing MMT. SeeFuel Additives
on page 9‑86 for additional
information.
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 might
be affected. The malfunction
indicator lamp could turn on and the
vehicle might fail a smog‐check test.
See Malfunction Indicator Lamp on
page 5‑25. 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 might not be covered by the
vehicle warranty.

Black plate (87,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-87
Some gasolines that are
not reformulated for low
emissions can contain an
octane-enhancing additive
called methylcyclopentadienyl
manganese tricarbonyl (MMT);
ask the attendant where you buy
gasoline whether the fuel contains
MMT. We recommend against
the use of such gasolines. Fuels
containing MMT can reduce
spark plug life and affect emission
control system performance.
The malfunction indicator lamp
might turn on. If this occurs,
return to your dealer for service.
Fuel E85 (85% Ethanol)
Vehicles that have a FlexFuel badge
and a yellow fuel cap can use either
unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85).
For all other vehicles, use only the
unleaded gasoline described under
Recommended Fuel on page 9‑84.We encourage the use of E85 in
vehicles that are designed to use it.
The ethanol in E85 is a
“renewable”
fuel, meaning it is made from
renewable sources such as corn
and other crops.
Many service stations will not have
an 85% ethanol fuel (E85) pump
available. The U.S. Department
of Energy has an alternative fuels
website (www.afdc.energy.gov/afdc/
locator/stations/) that can help you
find E85 fuel. Those stations that
do have E85 should have a label
indicating ethanol content. Do not
use the fuel if the ethanol content is
greater than 85%.
At a minimum, E85 should meet
ASTM Specification D 5798.
By definition, this means that fuel
labeled E85 will have an ethanol
content between 70% and 85%.
Filling the fuel tank with fuel
mixtures that do not meet ASTM
specifications can affect driveability
and could cause the malfunction
indicator lamp to come on. To ensure quick starts in the
wintertime, the E85 fuel must be
formulated properly for your climate
according to ASTM specification
D 5798. If you have trouble starting
on E85, it could be because the
E85 fuel is not properly formulated
for your climate. If this happens,
switching to gasoline or adding
gasoline to the fuel tank can
improve starting. For good starting
and heater efficiency below 0°C
(32°F), the fuel mix in the fuel tank
should contain no more than 70%
ethanol. It is best not to alternate
repeatedly between gasoline and
E85. If you do switch fuels, it is
recommended that you add as
much fuel as possible
—do not
add less than 11 L (3 gal) when
refueling. You should drive the
vehicle immediately after refueling
for at least 11 km (7 mi) to allow
the vehicle to adapt to the change
in ethanol concentration.