Shell Oil Company is the United States-based subsidiary of Royal Dutch Shell, a multinational "oil major" of Anglo-Dutch origins, which is amongst the largest oil companies in the world. Approximately 22,000 Shell employees are based in the U.S. The U.S. head office is in Houston, Texas. Shell Oil Company, including its consolidated companies and its share in equity companies, is one of America's largest oil and natural gas producers, natural gas marketers, gasoline marketers and petrochemical manufacturers.Shell is the market leader through approximately 25,000 Shell-branded gas stations in the U.S. which also serve as Shell's most visible public presence. Shell Oil Company is a 50/50 partner with the Saudi Arabian government-owned oil company Saudi Aramco in Motiva Enterprises, a refining and marketing joint venture which owns and operates three oil refineries on the Gulf Coast of the United States.Shell products include oils, fuels, and card services as well as exploration, production, and refining of petroleum products. The Shell Oil Refinery in Martinez, California, the first Shell refinery in the United States, supplies Shell and Texaco stations in the West and Midwest.Shell gasolines previously included the RU2000 and SU2000 lines (later there was a SU2000E) but they have been superseded by the V-Power line.In 1997, Shell and Texaco entered into two refining/marketing joint ventures. One combined their Midwestern and Western operations and was known as Equilon. The other, known as Motiva, combined the Eastern and Gulf Coast operations of Shell Oil and Star Enterprise, itself a joint venture between Saudi Aramco and Texaco. After Texaco merged with Chevron in 2001, Shell purchased Texaco's shares in the joint ventures. In 2002, Shell began converting these Texaco stations to the Shell brand, a process that was to be completed by June 2004 and was called "the largest retail re-branding initiative in American business history."