EXXON <XON> EXTENDS MID-GRADE UNLEADED MARKETING Exxon Co U.S.A. said it is expanding marketing of its mid-grade unleaded gasoline along the U.S. East Coast. The Exxon Corp subsidiary said the changeover to the 89-octane unleaded fuel will begin late this month and early next in major markets in Virginia, Maryland, Florida, and the District of Columbia. The product was introduced in New York, New Jersey, Delaware, Connecticut, Rhode Island, Massachusetts, New Hampshire and the Philadelphia area late last year.