Gasoline Octane; Gasoline Specifications - Chevrolet 2007 Cobalt Owner's Manual

Gasoline Octane

If your vehicle has the 2.2L L4 engine (VIN
Code F), use regular unleaded gasoline with a
posted octane rating of 87 or higher. If the octane
rating is less than 87, you may 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, your engine
needs service.
If your vehicle has the 2.4L L4 engine (VIN Code B)
or the 2.0L Supercharged engine (VIN Code P), 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 Specifications
At a minimum, gasoline should meet ASTM
specification 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. See Additives
on page 278 for additional information.
277