Redesignated USNS "Mission Capistrano" (T‑AO‑112), she was transferred to the operational control of MSTS on the same date. She continued her service with MSTS until 1 January 1955 when she was placed out of service, struck from the Naval Vessel Register, and transferred to the Maritime Administration and laid up at the Beaumont, Texas Reserve Fleet. Reacquired by the Navy on 5 July 1956, she was transferred to MSTS on the same date and placed in service for further duty with MSTS. She continued her voyages along the world’s tanker routes transporting oil to and from the United States until early 1960, when she entered the Todd Pacific Shipyards at New Orleans, Louisiana for conversion to a "Sound Testing Ship." Reclassified USNS "Mission Capistrano" (AG‑162) on 1 July 1960 she was modified to carry an ultra‑high‑powered sonar transducer array some five stories high and several tons in weight. The transducer could be raised and lowered like a centerboard through the ship’s bottom. Upon completion of her conversion, she was placed in service as USNS "Mission Capistrano" (T-AG-162) (date unknown) and joined "Project Artemis," a project intended to ultimately produce a system that could detect submarines at long range.