2002 Ford Focus Owner Guide 4th Printing - Page 295

Maintenance and Specifications Octane recommendations Your vehicle is designed to use regular" unleaded gasoline with an (R+M)/2 octane rating of 87. We do not recommend gasolines 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. 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 qualified service technician. 87 (R+M)/2 METHOD 295