Big Oil's new weak spot: the refining business By: MarketWatch March 14, 2010 at 06:00 AM EDT Energy companies are facing a longer-term struggle even as the summer driving season approaches and the economy shows signs of life. Read More >> Related Stocks: Chevron Corp ConocoPhillips Exxon Mobil Tesoro Petroleum Co Totalenergies Se ADR Valero Energy Wal-Mart Stores, Inc.