Fuel; Fuel Requirements - Subaru WRX 2021 Owner's Manual

Fuel

CAUTION
Use of a fuel which is low in quality
or use of an inappropriate fuel
additive may cause engine damage.
& Fuel requirements
! 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 driveabil-
ity. However, you may notice a slight
decrease in maximum engine perfor-
mance while using 91 AKI (95 RON) fuel.
Use of 91 AKI (95 RON) fuel will not affect
your warranty coverage.
! Except STI
The engine is designed to operate using
unleaded gasoline with an octane rating
of 91 AKI (95 RON) or higher. If 91 AKI
(95 RON) fuel is not readily available,
unleaded gasoline with an octane rating of
87 AKI (90 RON) may be used.
Regular unleaded gasoline with an octane
rating of 87 AKI (90 RON) or higher may
also be used. Using regular unleaded
gasoline will not be detrimental to engine
durability, nor will it affect your warranty
coverage. However, depending on your
driving habits and conditions, you may
notice a decrease in maximum engine
performance, fuel economy or slight en-
gine vibration or knocking. If you experi-
ence any of these conditions while using a
lower octane rated fuel, you may want to
return to using 91 AKI (95 RON) octane
rated fuel as soon as possible. Addition-
ally, if your vehicle knocks heavily or
persistently, the use of 91 AKI (95 RON)
or higher grade unleaded gasoline is
required.
! Fuel octane rating
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.
Starting and operating/Fuel
! RON
This octane rating is the Research Octane
Number.
! AKI
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).
! 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.
! Reformulated gasoline
SUBARU supports the use of reformulated
gasoline when available. Reformulated
gasoline has been blended to burn more
cleanly and reduce vehicle emissions.
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