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Fuel E85 (85% Ethanol)
The 8th digit of your Vehicle Identification
Number (VIN) shows the code letter or number
that identifies your engine. You will find the VIN at
the top left of the instrument panel. See Vehicle
Identification Number (VIN) on page 388.
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 see Fuel on page 288. In all other engines,
use only the unleaded gasoline described under
Gasoline Octane on page 289.
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 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 check engine light 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 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 three gallons
(11 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.
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