Fuel; Fuel Requirements - Subaru 2004 Legacy Owner's Manual

Starting and operating

Fuel

Starting and operating
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.
3.0 Liter models
The 3.0 Liter engine is designed to operate using pre-
mium unleaded gasoline with an octane rating of 91
AKI or higher. Regular unleaded gasoline with an oc-
tane rating of 87 AKI may be used if necessary. For
optimum engine performance and driveability, it is rec-
ommended that you use premium grade unleaded
gasoline.
Fuel octane rating
This octane rating is the average of the Research Oc-
7-2
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
impair driveability and fuel economy.
California fuel
If your vehicle was certified to California Emission
Standards as indicated on the underhood tune-up la-
bel. It is designed to optimize engine and emission
control system performance with gasoline that meets
the clean burning low-sulfur California gasoline speci-
fications. If you live in any other state than California,
your vehicle will operate on gasoline meeting Federal
specifications. Gasoline sold outside California is per-
mitted to have higher sulfur levels, which may affect
the performance of your vehicle's catalytic converter