The El Dorado Refinery is located in El Dorado, Kansas, and is one of the largest refineries in the plains states and the Rocky Mountain region with a crude oil capacity of 135,000 barrels per day. The El Dorado Refinery can select from many different types of crude oil because of its direct access to the Cushing, Oklahoma hub, which is connected by pipelines to Canada. This access, combined with the El Dorado Refinery's complexity, gives it the flexibility to refine a wide variety of crude oils.

El Dorado's refined products are marketed primarily in the eastern slope of the Rocky Mountain region, which includes eastern Colorado (including the Denver metropolitan area), eastern Wyoming, and the plains states.