"... shushing locomotives by as much as 30 decibels, and eliminating idling noise and cooling fan noise. Gone too would be the risk of spills from fuel or lubricating oil."

Why no lubricating oil?  There would still be wheels/axles/transmission components.  Are these all to be lubricated with graphite somehow?  I suspect this is a minor error in the article.  The author was probably only thinking about the oil within the sump that lubricates the diesel engine components.  Mind you, I guess one could argue that it is grease rather than oil which typically lubricates the majority of the parts that I've mentioned above.