Subaru 2003 Legacy - Manual (Page 252)

7-2
Fuel
CAUTION
Use of a fuel which is low in quality or use of an inappropriate
fuel additive may cause engine damage.
J
Fuel requirements
B
2.5 Liter models
The 2.5 Liter engine is designed to operate using unleaded gasoline
with an octane rating of 87 AKI or higher.
B
3.0 Liter models
The 3.0 Liter engine is designed to operate using premium unleaded
gasoline with an octane rating of 91 AKI or higher. Regular unleaded
gasoline with an octane rating of 87 AKI may be used if necessary.
For optimum engine performance and driveability, it is recommended
that you use premium grade unleaded gasoline.
B
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. See your dealer or a qualified service techni-
cian if you use a fuel with the specified octane rating and your vehicle
knocks heavily or persistently.
B
Unleaded gasoline
The neck of the fuel filler pipe is designed to accept only an unleaded
gasoline filler nozzle. Under no circumstances should leaded gaso-
line be used because it will damage the emission control system and
may impair driveability and fuel economy.