1999 Mercury Villager Owner's Manual - Page 219

Maintenance and care Octane recommendations Your vehicle is designed to use "Regular" unleaded gasoline with an (R+M)/2 octane rating of 87. We do not recommend the use of gasolines (R+M)/2 METHOD labeled as "Regular" that are sold with octane ratings of 86 or lower in high altitude areas. Do not be concerned if your engine sometimes knocks lightly. However, if it knocks heavily under most driving conditions while you are using fuel with the recommended octane rating, see your dealer or a qualified service technician to prevent any engine damage. 87 Fuel quality If you are experiencing starting, rough idle or hesitation driveability problems during a cold start, try a different brand of "Regular" unleaded gasoline. "Premium" unleaded gasoline is not recommended (particularly in the United States) because it may cause these problems to become more pronounced. If the problems persist, see your dealer or a qualified service technician. It should not be necessary to add any aftermarket products to your fuel tank if you continue to use a high quality fuel. Aftermarket products could cause damage the fuel system. Repairs to correct the effects of using a aftermarket product in your fuel may not be covered by your warranty. Many of the world's automakers issued the World-wide Fuel Charter that recommends gasoline specifications to provide improved performance and emission control system protection for your vehicle. Gasolines that meet the World-wide Fuel Charter should be used when available. Cleaner air Ford approves the use of reformulated "cleaner-burning" gasolines to improve air quality. These gasolines may contain oxygenates up to 10% ethanol or 15% MTBE. Running out of fuel Avoid running out of fuel because this situation may have an adverse affect on powertrain components. 219