GM YUKON XL Automobile User Manual


 
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 69
. For all other vehicles,
use only the unleaded gasoline described under
Gasoline Octane on page 67.
Gasoline Octane
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.
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
At a minimum, gasoline should meet ASTM
specification D 4814 in the United States or
CAN/CGSB3.5 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. See Additives
on page 68
for additional
information.
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