And both had about the same down-time. Steam took 5 minutes to find a problem, and 5 days to fix it. Diesels took 5 days to find a problem, and 5 minutes to fix it. Or vice-versa, dependent on the problem. In all honesty, when some of the early diesels were new, they ran quite well, with low emissions, for their time. Then railroads started losing money or funds, and maintenance slid, and these latter day problems, witnessed by later observers, form some basis of that view. Case in point:-I'm in the states, and saw Alco RS-3s belonging to both Penn Central and Gulf-Mobile and Ohio. Penn-Centrals smoked it up quite a bit, GM&O's did not. All in the maintenance.