Exxon Mobil Corp and Chevron Corp on Friday reported their most dismal quarterly results in more than a decade on low oil prices and an oversupplied fuel market that hurt what had been lucrative refining margins. As crude prices slid 60 percent from mid-2014, large integrated energy companies have touted the virtues of a business model that both produces oil and refines it. Refiners typically see profitability increase when the price of their main feedstock – oil – falls. But growing fuel inventories and weak demand are now hammering the refining industry, turning a typical advantage for integrated oil companies on its head. First-quarter pain in the downstream units, which came after major U.S. refiners slashed the amount of cheap crude they were processing in February, is a sign the road ahead for oil majors may turn […]