NEW GASOLINE GRADE TO RAISE U.S. REFINING COSTS A new grade of unleaded gasoline now being test marketed will increase refining costs when refiners can least afford it, according to officials attending the National Petroleum Refiners Association conference here. The new grade of unleaded gasoline has an octane level of 89 compared with over 90 for super unleaded and 87 for regular unleaded gasoline. Amoco Corp <AN> has test-marketed the new mid-grade gasoline and hopes to sell it on a regular basis in the South, East and Midwest by the beginning of June, according to Paul Collier, executive vice president of marketing. Phillips Petroleum <P> expects to begin marketing the new 89 octane unleaded gasoline in May, sources said. Converting current refinery operations to produce the 89 octane unleaded gsoline could cost hundreds of millions of dollars per refinery but that depends on the present capacity and intensity of the refinery, said Amoco's Collier. But not all oil company's welcome the introduction of another grade of unleaded gasoline. "Three grades are not warranted," said Henry Rosenberg, chairman of Crown Central Petroleum <CNP>. "Refiners will have to upgrade again," he added. "An investment will have to be made," said Archie Dunham, executive vice president of petroleum products at Conoco, an operating subsidiary of DuPont Corp <DD> in order to upgrade refinery operations.