Gasoline Octane; Gasoline Specifications; California Fuel - Hummer H2 2010 Owner's Manual

Gasoline Octane

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/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. See Additives on page 6 8 for additional
information.

California Fuel

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 4 34. 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.
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