I change mine every 4500 miles.
Not going longer than that, I don't care what some monitor tells me.
Towing, idling, 120F ambient air temps, stop/go traffic...... Oil is cheap.
Hmmmm, well 5 quarts is cheap but 3 Gallons, plus filter and plus, plus,plus.
The monitor takes all those variables into consideration.
Oil is not depleted even at 7500 mile.
All this 3000 mile oil change started with a purpose behind it, and it as follows.
The average business man, soccer mom etc. drives 10-12k per year, and would never open the hood of their car unless oil light went on or there was a strange noise of some kind. So since oil is cheap the answer was change every 3000 miles, and while we are in there we'll top off all fluids and check battery and whatever else we can sell you. that way we get a steady customer and you have a safe vehicle that's checked-over 4 times a year, win win for all, and then it became the standard.( you'll notice manufactures numbers are higher, 5-7 K miles) The oil companies keep brewing up better and better oil and more expensive too, now they have a captive audience, Remember have to change every 3K.
Well the truth is you don't. independent labs and articles have been written saying that used oil At 3K is not nearly spent, sometimes not even half life.
You have 3+ gallons in a 6.7L engine, yes it's a diesel and yes it has more carbon and is dirtier but you have 3 time more oil too.
I'm not super rich and i'm not poor either, I waste money by accident all the time, i'm not going to do it on purpose.
Some very interesting articles written on the subject and lab studies.
4500k your oil is probably in great shape, Just saying.