SP 5623's first assignments were passenger trains in Oregon, and then spent the rest of its passenger service career in the San Francisco Bay Area, pulling such trains as the Senator,Sacramento Daylight,Del Monte, and the San Francisco Peninsula commuter trains. SP 5623 was renumbered 3005 and painted into the grey and scarlet "bloody nose" paint scheme in 1966. After Amtrak assumed intercity passenger train service in 1971, SP 5623 (then numbered 3005) and all other SP passenger locomotives were assigned only to the SF Peninsula commuter trains. It was renumbered 3189 in 1977 after being rebuilt as a part of the SP's GRIP program. In 1985, it was displaced by the arrival of Caltrain equipment. It was then placed into local freight service for the rest of its regular service years.