Subaru 2006 Impreza WRX - Manual (Page 199)

7-2
Starting and operating
Starting and operating
Fuel
Fuel requirements
2.5-liter non-turbo models
The 2.5-liter non-turbo engine is designed
to operate using unleaded gasoline with
an octane rating of 87 AKI or higher.
WRX
The 2.5-liter turbo engine is designed to
operate using premium unleaded gasoline
with an octane rating of 91 AKI or higher.
If premium unleaded gasoline is not avail-
able, regular unleaded gasoline with an
octane rating of 87 AKI or higher may be
temporarily used. For optimum engine
performance and driveability, it is required
that you use premium grade unleaded
gasoline.
NOTE
Be sure to use premium unleaded gas-
oline of 91 AKI or higher for WRX. If
other gasoline (lower than 91 AKI) is
used, knocking, reduced output and
poor accelerator response will result.
WRX-STI
The 2.5-liter turbo engine is designed to
operate using super-premium unleaded
gasoline with an octane rating of 93 AKI or
higher. If super-premium unleaded gaso-
line with an octane rating of 93 AKI or
higher is not available, premium unleaded
gasoline with an octane rating of 91 AKI or
higher may be temporarily used. For opti-
mum engine performance and driveability,
it is required that you use super-premium
grade unleaded gasoline with an octane
rating of 93 AKI or higher.
NOTE
Be sure to use super-premium unlead-
ed gasoline of 93 AKI or higher for
WRX-STI. If other gasoline (lower than
93 AKI) is used, knocking, reduced out-
put and poor accelerator response will
result.
Fuel octane rating
This octane rating is the average of the
Research Octane and Motor Octane num-
bers and is commonly referred to as the
Anti Knock Index (AKI).
Using a gasoline with a lower octane rat-
ing can cause persistent and heavy
knocking, which can damage the engine.
Do not be concerned if your vehicle some-
times knocks lightly when you drive up a
hill or when you accelerate. See your
dealer or a qualified service technician if
you use a fuel with the specified octane
rating and your vehicle knocks heavily or
persistently.
Unleaded gasoline
The neck of the fuel filler pipe is designed
to accept only an unleaded gasoline filler
nozzle. Under no circumstances should
leaded gasoline be used because it will
damage the emission control system and
may impair driveability and fuel economy.
Gasoline for California-certified LEV
Your vehicle was certified to California’s
low emission vehicle (LEV) standards as
indicated on the underhood tune-up label,
it is designed to optimize engine and
emission performance with gasoline that
meets the clean burning low-sulfur Califor-
nia gasoline specifications. If you live in
any other state than California, your vehi-
cle will operate on gasoline meeting Fed-
eral specifications. Gasoline sold outside
California is permitted to have higher sul-
fur levels, which may affect the perfor-
mance of your vehicle’s catalytic convert-
er and may produce a sulfur exhaust odor
or smell. SUBARU recommends that you
try a different brand of unleaded gasoline
having lower sulfur to determine if the
Use of a fuel which is low in quality
or use of an inappropriate fuel addi-
tive may cause engine damage.