1996 Mercury Sable Owner's Manual - Page 292

RWARNING If you lose the fuel cap, replace it with one that is an authorized Motorcraft service part or an equivalent part. If you do not use the proper fuel cap, the pressure in the fuel tank can damage the fuel system or cause it to work improperly in a collision, endangering you and your passengers. NOTE: If you replace your fuel cap with an aftermarket fuel filler cap, the customer warranty may be void for any damage to the fuel tank and/or fuel system. Choosing the Right Fuel Use only UNLEADED FUEL. Using leaded fuel is prohibited by federal law. Any vehicle damage may not be covered by your warranty. Octane Recommendations Your vehicle is designed to use regular fuel with an octane rating of 87. In most cases it is not necessary to use a fuel with an octane rating higher than 87. At service stations, the octane rating is displayed in a label on the pumps. 265