The >10% fuel is somewhat shocking. As is the low TBN after relatively low mileage.
Do you live in a state with emission inspections?
If not I would quickly acquire the software/hardware to remove EGR (which is destroying the alkaline acid neutralization in the last 2 UOAs) and DPF (which is filling your sump with fuel via the "9th injector")
The lube is at risk here. Fuel is the number one issue, and as Charlie noted the TBN could be cause for alarm, but we'd really need to know TAN as well to understand how far it may or may not have turned.
However, the engine itself is fine. There's not any real metal count indicating that the lube has allowed any detrimental effect. Seems that Fe and Al are in line with reasonable wear rates, and the others (Pb, Cu, Cr and Ni) are all fine. Despite a generally fuel rich and EGR rich condition, the engine is handling it well. Si is low and has stayed that way; no concern there.
What this UOA shows is that there is not a direct, but indirect relationship between the lube and the engine. The lube is at risk; it should be monitored and controlled. The engine, however, seems unphased by the general state of the lube. There's nothing from the engine's point of view that screams at you. This is a great example of how cautionary notes do not always result in actual effect. If you were to use the lubes in ever increasing OCIs, then I would expect at some point to see wear rates affected. But at this point, you've not reached that the apex yet.
Just because you don't short trip or idle a great deal, that does not mean you're not also getting a lot of regen cycles. These newer diesels need to be operated under heavy load, often, to keep the EGT up, which in turn burns cleaner in the cyls and DPF. If you are running with little to no load, then you're not generating a lot of EGT, and so the regens will be more frequent. That would at least partially explain the fuel, etc. I cannot assure you this is the case, but it is a potential cause. More understanding of your actual loading and use of the truck would help here.
I would recommend, if simplicity is your goal, simply following the IOLM and continued monitoring for a while.
Also, your thread title shows 15w-40, but the report shows 5w-40 (as does your sig line). Which is it in this report? If you're actually running the syn, you might consider switching back to the conventional lube; longer OCIs are not likely to be pragmatic and therefore you could be saving money.
Oil is delo 15w-40. Typo in my sig. I went to that oil for the exact reasons you suggest dnewton, syn is wasted money in these engines. I also am keeping oci between 7k and 9k for the same reasons. I have 5 gallons of $$ syn here that I am going to have to use eventually
I tow more in what we jokingly call winter. My regens now are between 100 and 300 miles depending on how much highway I am driving. When towing regens go as long as 500 or 600 miles.
FWIW and not to start an argument but I am not going to delete this truck. I for one like clean air and willing to put up with the pain of trying to get there. I remember the smog in NYC when I was a kid and don't want to see that again.
I can respect the effort to retain the DPF, EGR, etc. I have not blocked my EGR or such on my Dmax, but I don't have regens with my LBZ.
If you're seeing regens every 100-300 miles, that would certainly be the reason your fuel in oil is where it's at. Not a lot you can do about it if "stock" condition is your intent. As you state, and it confirms my position, that heavy towing actually helps reduce fuel dilution by generating more EGT heat, which in turn requires less regens.
And as I mentioned, while the lube is pretty much nearing it's condemnation, the engine itself is none the worse for the wear. I'd stick to what you're doing. The engine is in good shape, you have a UOA history to show that OCI duration is managable and sustainable. Nothing wrong with what you're doing. Nothing at all.
Given your planned OCI pattern (which makes sense in your use), I'd buy whatever CJ-4 lube you can find on sale at the time. You'll not be running them long enough to really find any discernable performance difference; the fuel will contaminate any lube with no regard for brand loyality. Might as well buy the least expensive CJ-4 you can find and save. I'm not saying there is a "better" oil than Delo here; it did fine. But I think any brand (Delvac, Rotella, TE, VPB and even good house brands) would likely do as well. The lube will be contaminated by the fuel, with no respect for what company put it in the bottle. So if you can find a savings by capitalizing on a sale at the time of purchase, then go for it!
I think you're 100% on the right track here. The lube is nearing an end of its useful life. The engine is well protected at these durations; the metals say so. You're saving money. Congrats on using a UOA for a practical, managed decision!
Yes, I certainly respect your decision also.
BTW, I misspoke when I mentioned "9th injector". Actually your engine must have in-cylinder regeneration overinjection in the exhaust stroke which is what gives the high fuel conc. in the sump.
A post engine "9th injector" does not give fuel dilution.