The new trucks have monitors that tell you when you need to change the oil or fuel filters. The interval isn't any shorter than it is with gas engines. There are two fuel filters tho (at least on Fords). They recommend that you drain a small amount of fuel out of the filter (water separator) when you fuel up. It's right under the driver's seat.
These trucks take a lot of oil, about 15 Qt or Liters and the set of fuel filters (about every 15,000 mi (24000 km) is pricey--around US$50. So that is the major expense difference for routine maintenance.