Subaru 2004 Impreza - Manual (Page 271)

7-2
Starting and operating
Starting and operating
Fuel
Use of a fuel which is low in quality or use of an
inappropriate fuel additive may cause engine
damage.
! Fuel requirements
! 2.5 Liter models
The 2.5 Liter engine is designed to operate using un-
leaded gasoline with an octane rating of 87 AKI or
higher.
! 2.0 Liter (turbo) models
The 2.0 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
available, regular unleaded gasoline with an octane
rating of 87 AKI or higher may be temporarily used.
For optimum engine performance and driveability, it is
recommended that you use premium grade unleaded
gasoline.
! 2.5 Liter (turbo) model
The 2.5 Liter turbo engine is designed to operate using
super-premium unleaded gasoline with an octane rat-
ing of 93 AKI or higher. If super-premium unleaded
gasoline with an octane rating of 93 AKI or higher is
not available, premium unleaded gasoline with an oc-
tane rating of 91 AKI or higher can be used. For opti-
mum engine performance and driveability, it is recom-
mended that you use super-premium grade unleaded
gasoline with an octane rating of 93 AKI or higher.
! Fuel octane rating
This octane rating is the average of the Research Oc-
tane and Motor Octane numbers and is commonly re-
ferred 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 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 cir-
cumstances should leaded gasoline be used because
it will damage the emission control system and may