I think they are using diesel........
Well they aren’t converting the diesels. They must be buying new trucks. They are probably doing that because of the new diesel regulations. The new filters on the exhaust side must have the particulate burned out of them using a “regen” cycle. This isn’t a big problem for trucks operated mostly on the highway, but for fire engines, garbage trucks and other diesel trucks used mostly around town... it is a huge hassle and waste of fuel. They must leave the truck running for hours at high rpms with a fuel and regen fluid mixture being injected directly into the filter assembly to burn out the particulate. It is one of the stupidest things that the EPA has come out with recently and is causing lots of firms to turn from diesel for local use.