I have been on a reading kick. It's always interesting to re-read my railroad books, because every time I read, I see something that I missed previously. One of the best books on my shelves is One Man's Locomotives by Vernon Smith, a Mechanical Engineer who had a varied career in locomotive development and management, including a number of years with Santa Fe while the dieselization was in progress.
One of the chapters tells about his being asked to do a study for electrification of the main line between Winslow and Barstow. The cost then (October, 1944) for Bunker C residual oil for steam engines was 2.2 cents per gallon, and diesel fuel was 4.096 cents per gallon.