Subaru WRX STI Owner's Manual page 593

Fuel:
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.
Except STI
Use 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.
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). Refer to Fuel octane rating
GAS STATION REFERENCE
Fuel capacity:
15.9 US gal (60 liters, 13.2 Imp gal)
Engine oil:
Use only the following oils.
. ILSAC GF-5, which can be identified with the ILSAC
certification mark (Starburst mark)
. or API classification SN with the words ENERGY CON-
SERVING or RESOURCE CONSERVING
For the complete viscosity requirements, refer to Engine oil
12-4.
Engine oil capacity:
STI
4.5 US qt (4.3 liters, 3.8 Imp qt)
Except STI
5.4 US qt (5.1 liters, 4.5 Imp qt)
The indicated oil quantity is only a guideline and is estimated
based on a case when the engine oil is changed with an oil
7-3.
filter. After refilling the engine with oil, the oil level should be
checked using an oil level gauge. For more details about
maintenance and service, refer to Engine oil
Cold tire pressure:
Refer to Tires
I n f o r ma t i o n P r o v i d e d b y :
12-8.
11-13.