1996 Ford Explorer Owner's Manual - Page 343

Servicing Your Explorer In some parts of the country, "premium" grade fuels are sold with octane ratings of less than 91, especially in high altitude areas. It is recommended that you use only those "premium" fuels with an octane rating of 91 or higher. 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: s minimizing deposits in fuel injectors, combustion chambers and on intake valves. s assuring quick starting and smooth warm-up. s protecting the fuel system from vapor lock in very hot weather, which causes the engine to hesitate or stall and makes restarts difficult. s protecting your fuel system from rusting. s preventing the fuel lines from freezing. s preventing the fuel system from "gumming up" when your vehicle is not used for long periods of time. It should not be necessary to add any aftermarket products to your fuel tank if you continue to use a high-quality fuel. 343