GMC 2009 Savana, Owner'S Manual, Page: 248 / 406

Gasoline Octane
Use regular unleaded gasoline with a posted octane
rating of 87 or higher. If the octane rating is less than 87,
you might notice an audible knocking noise when you
drive, commonly referred to as spark knock. If this occurs,
use a gasoline rated at 87 octane or higher as soon as
possible. If you are using gasoline rated at 87 octane or
higher and you hear heavy knocking, 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 5-7
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 3-34. If this occurs, return to your
authorized dealer/retailer 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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