Subaru Outback Manuals 2017 Outback Owner's Manual | Page 374

Starting and operating/Fuel Fuel CAUTION Use of a fuel which is low in quality or use of an inappropriate fuel additive may cause damage to the engine and/or fuel system. & Fuel requirements The engine is designed to operate using unleaded gasoline with an octane rating of 87 AKI (90 RON) or higher. ! 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. 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. ! RON This octane rating is the Research Octane Number. ! AKI 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). ! 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. ! California fuel If your vehicle was certified to California Emission Standards as indicated on the underhood tune-up label, it is designed to optimize engine and emission control system performance with gasoline that meets the clean burning low-sulfur California gasoline specifications. If you live in any other state than California, your vehicle will operate on gasoline meeting Federal specifications. Gasoline sold outside California is permitted to have higher sulfur levels, which may affect the performance of your vehicle’s catalytic converter and may produce a sulfur exhaust odor or smell. SUBARU recommends that you try a different brand of unleaded gasoline having lower sulfur to determine if the problem is fuel related before returning 7-3 your vehicle to an authorized dealer for service. The CHECK ENGINE warning light/malfunction indicator light may also turn on. If this occurs, return to your authorized SUBARU dealer for diagnosis. If it is determined that the condition is caused by the type of fuel used, repairs may not be covered by your warranty. ! MMT Some gasoline contains an octane-enhancing additive called MMT (Methylcyclopentadienyl Manganese T