eiauto - welcome to the site!
I'll offer some perspective, not knowing how well versed you are in the 6.0PSD. A bit of advice from which I have personal knowledge, and it would relate to your search for insight in the UOA ...
The 6.0PSD has many issues; most are well known. But nearly all of them stem from one root cause; a blocked oil cooler on the coolant side. That snowballs into all kinds of issues, not the least of which ends up being a restriction of the flow of coolant through the system. The EGR will overheat because the coolant cannot move through it, which in turn overheats the heads and spits out the coolant degas tank; it also can micro-crack the EGR tube(s) resulting in oil/water mixing. Further, with no coolant flow, the oil will overheat (no cooling effect) that results in coked turbo. I also suspect that this can aggrevate the viscosity break down; a condition that is (knee-jerk) blamed on the HEUI. (Probably a combination of the two; HEUI with overheated lube).
I have directly seen all these things on my neighbor's 1995 PSD. We worked on it a bit, and he had the turbo replaced (twice), the EGR cooler replaced, a new OEM oil cooler installed with screen, and new oil gallery o-rings (and some other issues not directly related). We did not do all the work ourselves, because he had purchased an extended warrnaty; boy-oh-boy did that ever pay for itself in this case. Like I said; the plugged cooler is the root cause and it wreaks havoc throughout the system.
Two things done preventively might keep this from happening:
1) coolant dump, flush and refill
2) adding a coolant bypass filter (many aftermarket ones available)
It is genearlly agreed (and I've seen first hand evidence) that the coolant passages on the oil/water cooler are too small, and they plug with debris. At 200k miles, I suspect you already have the problem fully developed, or at least mostly plugged. But it would be worth it for you to try a flush and filter, before you have to tear into the whole engine. It is quite an ordeal if you have to replace the EGR, the oil cooler, the turbo, etc. Major undertaking and big dollars.
I have always wondered what would be the effect if someone with a very low mileage 6.0PSD installed a coolant filter early, and stopped the condition before it started, with a good flush/filter set up. That would take care of a LOT of the problems that plague the sick-point-oh.
Tying this in with your UOA, I'd say there are small, but possible signs, of coolant intrusion. But it's not a 100% assurance. But I mention all this because if you start to see even the hint of coolant spilling, coolant loss, coolant in the oil, etc it is probably too late. By that time, the bulk of the oil cooler is probably plugged up, and there is no way to "clean" it. When you remove it (a major PITA because it is under the oil filter mount) they cannot typically be salvaged; they often must be replaced. I don't know of anyone who has saved a blocked cooler. There are even kits to bypass the OEM oil cooler and install air/oil set-ups. If you lose coolant when in a tow tune, but not in stock tune, it's already in play. I'd say, considering that you have 200k miles on it, and with your suspicisions and statements, it's certainly possible you're on the cusp of big repairs in the future.
