2012 Jeep Wrangler Owner Manual - Page 462

460 STARTING AND OPERATING FUEL REQUIREMENTS All engines are designed to meet all emissions regulations and provide excellent fuel economy and performance when using high quality unleaded "regular" gasoline having an octane rating of 87. The use of premium gasoline is not recommended, as it will not provide any benefit over regular gasoline in these engines. Over 40 auto manufacturer's worldwide have issued and endorsed consistent gasoline specifications (the Worldwide Fuel Charter, WWFC) to define fuel properties necessary to deliver enhanced emissions, performance, and durability for your vehicle. The manufacturer recommends the use of gasoline that meets the WWFC specifications if they are available. Reformulated Gasoline Many areas of the country require the use of cleaner Light spark knock at low engine speeds is not harmful to burning gasoline referred to as "Reformulated Gasoline." your engine. However, continued heavy spark knock at Reformulated gasoline contains oxygenates, and are spehigh speeds can cause damage, and immediate service is cifically blended to reduce vehicle emissions and imrequired. prove air quality. Poor quality gasoline can cause problems such as hard The manufacturer supports the use of reformulated gasostarting, stalling and hesitations. If you experience these line. Properly blended reformulated gasoline will prosymptoms, try another brand of gasoline before considvide excellent performance and durability for the engine ering service for the vehicle. and fuel system components.