2007 Dodge Ram 1500 Pickup Owner's Manual - Page 380

380 STARTING AND OPERATING FUEL REQUIREMENTS All engines (except 5.7L 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 3.7L/4.7L of 87. The routine use of premium gasoline Engines is not recommended. Under normal conditions the use of premium fuel will not provide a benefit over high quality regular gasolines and in some circumstances may result in poorer performance. 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 manu5.7L Engines facturer recommends the use of 89 octane for optimum performance.The routine use of premium gasoline is not recommended. The use of premium gasoline will provide no benefit over high quality regular and mid-grade gasolines, and in some circumstances may result in poorer performance. Light spark knock at low engine speeds is not harmful to your engine. However, continued heavy spark knock at high speeds can cause damage and immediate service is required. Poor quality gasoline can cause problems such as hard starting, stalling and hesitations. If you experience these symptoms, try another brand of "regular" gasoline before considering service for the vehicle. Over 40 auto manufacturers world-wide 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. We recommend the use of gasolines that meet the WWFC specifications if they are available.