the engine was supplied by three single-ended Scotch marine boilers fitted for oil fuel. The sea trials were held on 2 March 1921 with the ship performing satisfactorily. Following their successful completion Montebello was handed over to her owners on March 4 and after applying final touches commissioned on March 9. Operational history Following delivery and commissioning, Montebello left Los Angeles for Port San Luis, the major oil storage and shipping facility for Union Oil, and arrived there on 10 March 1921. After loading a cargo of 81,000 barrels of oil the tanker left for San Francisco and reached her destination on March 12, successfully concluding her maiden voyage. Upon unloading the tanker departed San Francisco on March 14 bound for Vancouver via Port San Luis. After taking on board 41,000 barrels of fuel oil and 40,000 barrels of diesel fuel the tanker sailed out from Port San Luis on March 17 and reached her destination five days later. On her third trip the ship traveled to Puerto Lobos, one of the major oil storage ports in Mexico, and returned to San Pedro on 14 May 1921 carrying 11,000 tons of oil. The tanker then remained berthed in harbor until the end of August, and then re-entered the coast-wise service. As part of her service Montebello carried oil from Port San Luis to Union Oil refinery in Oleum, or from San Pedro to storage and refinery facilities at Martinez. She also made occasional trips along the Pacific coast to ports such as Vancouver, Portland or Seattle, and on occasion took her cargo to Honolulu. In 1924 the tanker became more involved in long haul operations conducting voyages to Hawaii and Canada with more frequency. In addition, Montebello started making trips to Balboa in the Panama Canal area and Chilean ports of Antofagasta, Iquique and Taltal. For example, on 8 July 1924 she delivered 10,000 tons of fuel oil to Balboa and on 6 January 1925 she left San Pedro carrying 76,801 barrels of oil bound for Antofagasta. In 1926 the service to the Panama Canal and Chile picked up significantly and became the tanker's primary routes of operation. Montebello remained in this service for the next five years at which point she was slowly over the next two years shifted back to coastline service along the West coast and to Hawaii. During the night of 5 October 1930 while the