2010 Dodge Ram 1500 Regular Cab Owner Manual - Page 434

432 STARTING AND OPERATING 5.7L Engine The 5.7L engine is designed to meet all emissions regulations and provide satisfactory fuel economy and performance when using high quality unleaded gasoline having an octane range of 87 to 89. The manufacturer recommends the use of 89 octane for optimum performance. The use of premium gasoline is not recommended, as it will not provide any benefit over regular gasoline in these engines. Over 40 auto manufacturers worldwide have issued and endorsed consistent gasoline specifications (the Worldwide Fuel Charter, WWFC) which 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 burning gasoline referred to as "Reformulated Gasoline." Light spark knock at low engine speeds is not harmful to Reformulated gasolines contain oxygenates and are speyour engine. However, continued heavy spark knock at cifically blended to reduce vehicle emissions and imhigh speeds can cause damage and immediate service is prove air quality. required. Poor quality gasoline can cause problems such The manufacturer supports the use of reformulated gasoas hard starting, stalling, and hesitations. If you experilines. Properly blended reformulated gasolines will proence these symptoms, try another brand of gasoline vide excellent performance and durability for the engine before considering service for the vehicle. and fuel system components.