Good question. I've been doing it for years.

Some of those Cummins diesels hold 20 to 30 quarts.

If your fire chief is that foolish, tell him he needs Rotella T6 and then if he'll let you have it use it for anything.

Changing oil at 200 miles is probably doing more harm than good. Make sure you pre-fill the diesel oil filters especially the big ones.

Freightliner told me to use synthetic and change the filter at 10,000 miles and then change oil at 20,000. Some truckers go nearly a 100,000 miles just using a regular analysis and filter change.

Oil is way to expensive to change more often than necessary. Same for diesel air and fuel filters. Diesel fuel is much cleaner than it used to be.