2007 GMC SIERRA CLASSIC engine

If your vehicle has the 6.0L V8 engine
(VIN Code N), use premium unleaded gasoline
with a posted octane rating of 91 or higher.
You may also use regular unleaded gasoline rated
at 87 octane or higher, but your vehicle’s
acceleration may be slightly reduced, and you
may notice a slight audible knocking noise,
commonly referred to as spark knock. If the octane
is less than 87, you may 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 might damage your
engine. If you are using gasoline rated at
87 octane or higher and you hear heavy knocking,
your engine needs service.
Gasoline Specications
At a minimum, gasoline should meet ASTM
specication D 4814 in the United States or
CAN/CGSB-3.5 in Canada. Some gasolines may
contain an octane-enhancing additive called
methylcyclopentadienyl manganese tricarbonyl
(MMT). General Motors recommends against the
use of gasolines containing MMT. SeeAdditives
on page 472for additional information.
California Fuel
If your vehicle is certied to meet California
Emissions Standards, it is designed to operate on
fuels that meet California specications. See the
underhood emission control label. If this fuel is not
available in states adopting California emissions
standards, your vehicle will operate satisfactorily on
fuels meeting federal specications, but emission
control system performance may be affected. The
malfunction indicator lamp may turn on and your
vehicle may fail a smog-check test. SeeMalfunction
Indicator Lamp on page 258. If this occurs, return to
your authorized GM dealer for diagnosis. If it is
determined that the condition is caused by the type
of fuel used, repairs may not be covered by your
warranty.
471

Additives
To provide cleaner air, all gasolines in the United
States are now required to contain additives
that will help prevent engine and fuel system
deposits from forming, allowing your emission
control system to work properly. In most cases,
you should not have to add anything to your
fuel. However, some gasolines contain only the
minimum amount of additive required to meet U.S.
Environmental Protection Agency regulations.
To help keep fuel injectors and intake valves clean,
or if your vehicle experiences problems due to
dirty injectors or valves, look for gasoline that is
advertised as TOP TIER Detergent Gasoline.
Also, your GM dealer has additives that will help
correct and prevent most deposit-related problems.
Gasolines containing oxygenates, such as
ethers and ethanol, and reformulated gasolines
may be available in your area. General Motors
recommends that you use these gasolines if they
comply with the specications described earlier.
However, E85 (85% ethanol) and other fuels
containing more than 10% ethanol must not be
used in vehicles that were not designed for
those fuels.Notice:Your vehicle was not designed for
fuel that contains methanol. Do not use
fuel containing methanol. It can corrode metal
parts in your fuel system and also damage
the plastic and rubber parts. That damage
would not be covered under your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant where you
buy gasoline whether the fuel contains MMT.
General Motors recommends against the use of
such gasolines. Fuels containing MMT can reduce
the life of spark plugs and the performance of
the emission control system may be affected. The
malfunction indicator lamp may turn on. If this
occurs, return to your authorized GM dealer
for service.
472

Fuel E85 (85% Ethanol)
The 8th digit of your Vehicle Identication Number
(VIN) shows the code letter or number that
identies your engine. You will nd the VIN at
the top left of the instrument panel. SeeVehicle
Identication Number (VIN) on page 598.
If your vehicle has the 5.3L V8 engine
(VIN Code Z only), you may use either regular
unleaded gasoline or ethanol fuel containing up to
85% ethanol (E85); also seeFuel on page 470.
In all other engines, use only the unleaded
gasoline described underGasoline Octane on
page 470.
Only vehicles that have the 5.3L V8 engine
(VIN Code Z) may use 85% ethanol fuel (E85).
General Motors encourages 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.eere.energy.gov/afdc/infrastructure/
locator.html) that can help you nd 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
Specication D 5798.
To ensure quick starts in the wintertime, the
E85 fuel must be formulated properly for your
climate according to ASTM specication D 5798.
If you have trouble starting on E85, it may be
because your E85 fuel is not properly formulated
for your climate. If this happens, switching to
gasoline or adding gasoline to your fuel tank may
improve starting. For good starting and heater
efficiency below 32°F (0°C), 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 ve gallons
(18.9 L) when refueling. You should drive
the vehicle immediately after refueling for at least
seven miles (11 km) to allow the vehicle to
adapt to the change in ethanol concentration.
473

E85 has less energy per gallon than gasoline, so
you will need to rell your fuel tank more often
when using E85 than when you are using gasoline.
SeeFilling the Tank on page 474.
Notice:Some additives are not compatible
with E85 fuel and may harm your fuel system.
Damage caused by additives would not be
covered by your new vehicle warranty. Do not
use additives with E85 fuel.
Notice:Your vehicle was not designed for
fuel that contains methanol. Do not use
fuel containing methanol. It can corrode metal
parts in your fuel system and also damage
the plastic and rubber parts. That damage
would not be covered under your warranty.
Fuels in Foreign Countries
If you plan on driving in another country outside
the United States or Canada, the proper fuel may
be hard to nd. Never use leaded gasoline or
any other fuel not recommended in the previous
text on fuel. Costly repairs caused by use of
improper fuel would not be covered by your
warranty.To check the fuel availability, ask an auto club, or
contact a major oil company that does business
in the country where you will be driving.
Filling the Tank
{CAUTION:
Fuel vapor burns violently and a fuel re
can cause bad injuries. To help avoid
injuries to you and others, read and follow
all the instructions on the pump island.
Turn off your engine when you are
refueling. Do not smoke if you are near
fuel or refueling your vehicle. Keep
sparks, ames, and smoking materials
away from fuel. Do not leave the fuel
pump unattended when refueling your
vehicle. This is against the law in some
places. Keep children away from the fuel
pump; never let children pump fuel.
474

Checking Things Under
the Hood
{CAUTION:
An electric fan under the hood can start up
and injure you even when the engine is not
running. Keep hands, clothing, and tools
away from any underhood electric fan.
{CAUTION:
Things that burn can get on hot engine
parts and start a re. These include
liquids like fuel, oil, coolant, brake uid,
windshield washer and other uids, and
plastic or rubber. You or others could be
burned. Be careful not to drop or spill
things that will burn onto a hot engine.
478

Engine Compartment Overview
When you open the hood on the 4.3L V6 engine, here is what you will see:
480

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter (Gasoline Engines) on page 491.
B. Coolant Surge Tank and Pressure Cap. See
Engine Coolant on page 502andCoolant
Surge Tank Pressure Cap on page 505.
C. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter (Gasoline
Engines) on page 491.
D. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil (Gasoline Engine) on
page 486.
E. Automatic Transmission Fluid Dipstick
(If Equipped). See “Checking the Fluid Level”
underAutomatic Transmission Fluid (Allison
Transmission
®) on page 494orAutomatic
Transmission Fluid (Except Allison
Transmission
®) on page 497.
F. Engine Cooling Fan. SeeCooling System on
page 508.G. Engine Oil Fill Cap. See “When to Add Engine
Oil” underEngine Oil (Gasoline Engine) on
page 486.
H. Power Steering Fluid Reservoir. SeePower
Steering Fluid on page 515.
I. Remote Negative (−) Terminal (GND). See
Jump Starting on page 521.
J. Remote Positive (+) Terminal. SeeJump
Starting on page 521.
K. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 517.
L. Clutch Fluid Reservoir (If Equipped). See
Hydraulic Clutch on page 501.
M. Underhood Fuse Block. SeeUnderhood Fuse
Block on page 603.
N. Battery. SeeBattery on page 520.
O. Windshield Washer Fluid Reservoir. See
“Adding Washer Fluid” underWindshield
Washer Fluid on page 516.
481

When you open the hood on the 5.3L V8 engine (4.8L and 6.0L V8 engines similar), here is what you
will see:
482