In January 1989, Texaco and Saudi Aramco agreed to form a joint venture known as Star Enterprise in which Saudi Aramco would own a 50% share of Texaco's refining and marketing operations in the eastern U.S. and Gulf Coast. In 1989, Texaco introduced System3 gasolines in all three grades of fuel, featuring the latest detergent additive technology to improve performance by reducing deposits that clog fuel injection systems. Toronto-based Texaco Canada Incorporated was sold to Imperial Oil with all Texaco Canada retail operations converted to Esso brand. Two years later, the company was awarded the National Medal of Arts. In 1991, non retail Canadian operations became Texaco Canada Petroleum Incorporated with head office in Calgary, Alberta. In 1993, several dozen tribal leaders and residents from the Ecuadoran Amazon filed a billion-dollar class-action lawsuit against Texaco, as a result of massive ecological pollution of the area and rivers around Texaco's Ecuadorian offshore drilling sites, causing toxic contamination of approximately 30,000 residents.