Subaru WRX & WRX STI Manuals 2013 Impreza WRX & WRX STI Owner's Manual | Page 247

Starting and operating

Fuel
CAUTION
Use of a fuel which is low in quality
or use of an inappropriate fuel
additive may cause engine damage.

& Fuel requirements
! Except STI
The engine is designed to operate using
premium unleaded gasoline with an
octane rating of 91 AKI (95 RON) or
higher. If premium unleaded gasoline is
not available, regular unleaded gasoline
with an octane rating of 87 AKI (90 RON)
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
gasoline of 91 AKI (95 RON) or higher.
If other gasoline (lower than 91 AKI (95
RON)) is used, knocking, reduced output and poor accelerator response will
result.

! STI
The engine is designed to operate at
maximum performance using unleaded
gasoline with an octane rating of 93 AKI
(98 RON) or higher. If 93 AKI (98 RON)
fuel is not readily available in your area,
unleaded gasoline with an octane rating of
91 AKI (95 RON) may be used with no
detriment to engine durability or driveability. However, you may notice a slight
decrease in maximum engine performance while using 91 AKI (95 RON) fuel.
Use of 91 AKI (95 RON) fuel will not affect
your warranty coverage.
! Fuel octane rating
This octane rating is the average of the
Research Octane and Motor Octane
numbers and is commonly referred to as
the Anti Knock Index (AKI).
Using a gasoline with a lower octane
rating can cause persistent and heavy
knocking, which can damage the engine.
Do not be concerned if your vehicle
sometimes knocks lightly when you drive
up a hill or when you accelerate. Contact
your SUBARU dealer if you use a fuel with
the specified octane rating and your
vehicle knocks heavily or persistently.
! Unleaded gasoline
The neck of the fuel f