Premcor

{{Infobox company

| name = Premcor

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| industry = Oil Refining

| fate = Acquired by Valero

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| defunct = {{end date|2005}}

| hq_location_city = Greenwich, Connecticut

| hq_location_country = United States

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Premcor (formerly NYSE symbol PCO) was a Fortune 500 oil refinery group based in Greenwich, Connecticut. It operated five refineries, which are located in Port Arthur, Texas; Memphis, Tennessee; Lima, Ohio; Hartford, Illinois; and Delaware City, Delaware with a combined crude oil volume processing capacity of approximately {{convert|768120|oilbbl/d|m3/d}} (July, 2007).

Premcor was acquired by Valero in 2005. Valero would later sell the Lima facility to Husky Energy in July 2007 and close the Delaware City refinery in November 2009.