1996 Ford Aspire Owner's Manual - Page 181

Octane recommendations Your vehicle is designed to use regular unleaded fuel with an octane rating of 87. At service stations, the octane rating is displayed in a label on the pumps. Typical octane rating label In some parts of the country, "regular" grade fuels are sold with octane ratings of 86 or even less, especially in high altitude areas. We recommend that you do not use these fuels. Always use a fuel with an octane rating of 87, even if it is sold as a "midgrade" or "premium." Do not be concerned if your vehicle sometimes knocks lightly when you drive up a hill or when you accelerate. However, see your dealer or a qualified service technician if persistent, heavy knocking occurs because this can damage the engine. Fuel quality If you are experiencing starting, rough idle or hesitation problems when the engine is cold, it may be caused by fuel with low volatility. Try a different brand of fuel. If the condition persists, see your dealer or a qualified service technician. Using a high-quality fuel makes your vehicle more responsive and maintains its good fuel economy and emissions by: u protecting your fuel system from rusting. u preventing the fuel lines from freezing. 182