Pennzoil is an American oil company founded in Los Angeles, California in 1913. In 1955, it was acquired by Oil City, Pennsylvania company South Penn Oil, a former branch of Standard Oil. In 1963, South Penn Oil merged with Zapata Petroleum; the merged company took the Pennzoil name. During the 1970s, the company moved its offices to Houston, Texas. In 1977 a spin-off company was formed called Pogo, which stood for Pennzoil Offshore Gas Operators.
The Grand Prix of Houston will return to Reliant Park in 2013 with the IZOD IndyCar Series. The event will be known as the Shell and Pennzoil Grand Prix of Houston thanks to a multi-year title sponsorship agreement with Shell Oil Company.