23 Cascadia w/ DD15 oil change interval?

Pull an oil sample, then you will have some info on the type of runs you are doing. (Longer or shorter intervals)

 

The first one I did on my 2021 was 25k. But these modern engine have longer intervals now. It is based on your fuel mileage. If you're climbing the mountains and heavy it will be a shorter interval as running flatland and light. The oil sample will tell you what your engine is doing. I usually change mine around 35k-40k. My friend a mechanic at Ryder does them at 60k.

 

If you plan on keeping it....the cheapest insurance you can get for your motor is regular oil changes

 

Follow the recommendation from Detroit and reduce by 25% if you want extra insurance.

With synthetic you can easily go 35-50k miles with no downside as proven by used oil analysis.

Many manufacturers are going over 50k intervals now as long as your fuel economy is 7+ mpg.

The factories know what they're doing on these longer drains with the new, much cleaner burning engines.

 

The 75,000 mile number is used to keep the fleets happy. Generally they only keep the truck three or four years and don’t care what happens to it after that.
If you plan on having the truck for a longer time then a shorter interval would be a smarter choice.
I think the original DD15’s said 50,000 miles, so maybe that might be appropriate.
It also depends upon the duty cycle of the engine. On my 2012 hauling 140,000 lbs was considered severe service, 25,000 miles was the recommended interval. But I did it at 500 hours which was about 17,000 miles in my operation.
As mentioned, oil analysis would be a good idea to keep an eye on things. If the metal numbers get too high, then do a shorter interval.