The 3.0L and 3.3L engines are designed to operate on unleaded gasoline ONLY, and its use is essential for proper operation of the emission control system. The use of unleaded fuel will reduce spark plug fouling, exhaust system corrosion, and engine oil deterioration.
In most parts of the United States, fuel with an octane rating of 87 should be used, unless otherwise specified by the vehicle manufacturer for performance reasons. Using fuels with a lower octane rating may decrease engine performance, increase emissions, and cause persistent heavy knocking which may damage the engine. In addition, always use fuel with an -intake system deposit control- detergent that will help keep the intake valves and injectors clean.
Some fuel suppliers are producing reformulated gasolines which are designed to reduce vehicle emissions. These fuels may contain ethanol, methanol, and MTBE. If reformulated gasoline is used, it should contain no more than 5% methanol, 10% ethanol, or 15% MTBE.