Tesoro Corporation, a Fortune 100 company, is an independent refiner and marketer of petroleum products. Tesoro, through its subsidiaries, operates six refineries in the western United States with a combined capacity of 850,000 barrels per day. Tesoro’s retail-marketing system includes over 2,250 retail stations under the Tesoro®, Shell®, ARCO®, Exxon®, Mobil® and USA Gasoline™ brands.