Well you don't have to worry about spark plugs or throttles. On the other hand, there's smog systems. Also I know diesel engine parts are expensive. They do tend to last longer though.

Generally, the cost of maintenance on a diesel will be higher than on a gas engine.  Diesels hold more oil so the cost to change the oil will be higher.  Between the fuel and exhaust systems there are more filters and components that need to be changed.  Thanks to emissions requirements, diesel exhaust fluid will need to be added.  Additionally, in some places the cost of diesel gasoline can be higher than gasoline.   Finally, repairs costs are higher when things do break.

I recommend only getting diesel if you absolutely need it (say you tow often and/or tow very heavy loads).

Hello there!

If you are new to diesel engines, I suggest you read this (click there).

Good luck!

Depending on make/model/motor, injectors will be part of maintenance as well. Pumps and filters also. Other than that they pretty much just keep truckin along. I mean unless you mod it out and just run the piss out of it. Then you will be doing maintenance more frequently. My friends 2nd gen Cummins has topped 600k now and it runs like he just bought it new off the lot yesterday mountainmanjoe is right as well the parts are just built stronger and sturdier than on gas motors. Keep in mind also those diesel motors don’t even break in until around the 100k mark so they are built to last for sure.