A 1947 study compared the economic performance of the TI and Q2 steam locomotives to 6000 horsepower sets of diesels. These figures factored in maintenance, fuel, and other related costs, but did not take into account reduced expenses for labor with the elimination of steam helpers, reduced train crews because of multiple unit operation, and fewer trains required by using diesels. As these facts indicate, a railroad could achieve substantial savings in short and long term operating costs by dieselizing as quickly as possible. To put it simply, electrical transmissions match engine capabilities better than other systems. The electric transmission allows the engine to operate at the most efficient RPM and horsepower for the conditions of a railroad.
Most diesel locomotives use water as coolant.
If the unit is left shutdown for an extended period of time in freezing temperatures, the water will freeze. This could damage the locomotive since water expands as it freezes. Most railroads have rules that locomotives cannot be shut down in temperatures below 40 degrees unless the water is drained. Since starting diesels is time consuming, they are frequently left running even in warmer weather. Fuel consumption drops to only a few gallons per hour in idle mode.