Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Valero Energy Corporation (NYSE: VLO) is a Fortune 500 oil and gas refining and retail company based in San Antonio, Texas, United States. The company owns and operates 18 refineries throughout the United States, Canada and the Caribbean with a combined throughput capacity of approximately 3.3 million barrels per day, making it the largest refiner in North America. Valero is also one of the US''s largest retail operators with more than 5,000 retail and branded wholesale outlets in the United States, Canada and the Caribbean under various brand names, including Valero, Diamond Shamrock, Ultramar, Shamrock, and Beacon.