She was launched 7 January 1939 by Sun Shipbuilding and Drydock Company, Chester, Pennsylvania; sponsored by Mrs. William D. Leahy; and commissioned 20 March 1939.

After repairs and alterations, she began oil runs on the east coast, principally between Baton Rouge and Norfolk, until August 1941, when she took part in amphibious operations.

[1] From 5–16 September she put to sea with a transport convoy bound for Iceland, and voyaged north again from 12 October to 5 November to refuel ships at Placentia Bay.

She cleared Pearl Harbor on 28 May to fuel the force which defeated the Japanese in the Battle of Midway and returned on 12 June, departing on 7 July to support the operation in the Solomon Islands.

[1] Between July 1946 and June 1950, Cimarron ferried oil from the Persian Gulf to naval bases in the Marianas and Marshalls, occasionally continuing on to the US West Coast.

Several times she entered the heavily mined waters of Wonsan Harbor South Korea to fuel the ships carrying out the lengthy blockade and bombardment of that key port.

During this time she spent a month at Taiwan fueling the ships on duty in the Formosa Straits, and made three voyages to Korean waters from Sasebo.

[1] Cimarron sailed to the Far East again between 14 June 1954 and 8 February 1955, during which she served as flagship of the United Nations support group for Operation Passage to Freedom, the evacuation of refugees from Communist North Vietnam.