Fuel
If your vehicle has a diesel engine, see Diesel
Engine Fuel on page 248.
For vehicles with gasoline engines, please
read this.
Use of the recommended fuel is an important part
of the proper maintenance of your vehicle. To
help keep your engine clean and maintain optimum
vehicle performance, GM recommends the use
of gasoline advertised as TOP TIER Detergent
Gasoline.
Gasoline Octane
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.
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 247 for additional information.
Additives
To provide cleaner air, all gasolines in the United
States are now required to contain additives that
will help prevent engine and fuel system deposits
from forming, allowing your emission control system
to work properly. In most cases, you should not
have to add anything to your fuel. However, some
gasolines contain only the minimum amount of
additive required to meet U.S. Environmental
Protection Agency regulations. To help keep fuel
injectors and intake valves clean, or if your vehicle
experiences problems due to dirty injectors or
valves, look for gasoline that is advertised as TOP
TIER Detergent Gasoline. Also, your dealer has
additives that will help correct and prevent most
deposit-related problems.
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