Occidental Petroleum is a well-oiled machine. Occidental Petroleum (OXY -0.20%) recently reported impressive second-quarter results. The oil company posted robust oil and gas production in the period and expectations-beating earnings in its midstream and marketing segment. It also reported strong earnings and cash flow. The oil stock's robust results must be music to Warren Buffett's ears. As Occidental's top shareholder, Buffett's company, Berkshire Hathaway, is participating in Occidental's success, which ...