I use Delo 400 15/40 LE. The CJ formula. I stockpiled 24 Gallons while it was still available from local sources. When I run out, I'll evaluate the CK reports to get a feel for change interval on that oil. I feel the formulations make a difference.
2001 7.3 280,000 MILES).....I HAVE HAD THE TRUCK FOR ABOUT TWO YEARS.....IT IS ALMOST READY FOR THE ROAD.....
SO.....IN YOUR OPINION.....SHOULD I CHANGE MY OIL AND WAIT A FEW MONTHS.....FEW THOUSAND MILES AND HAVE MY OIL TESTED.....OR SHOULD I GO AHEAD AND TEST THE CURRENT OIL IN THE TRUCK BEFORE I CHANGE THE OIL?.....
The first thing to understand about Universal Oil Analyses is that you are looking for TRENDS. A single sample will show a serious problem in the trace metals, but will not tell you anything about how your engine is wearing normally, or how "hard" it is on oil the way you use your truck, that you can use to determine change interval. Use the same lab every time, use the same "unit identifier" for each sample and the report will show previous tests as well as the current one. Makes comparison, trends, and "problems" easy to spot.
I would sample the oil that is in it now. Try to drive it regularly for a few hundred miles, and sample the oil when it is warm, about half-way through the drain. Use your oil of choice, and sample it again at 5,000 miles. IF you are interested in extended drain intervals (more than 7,500 miles) I would suggest doing it in steps. Ie, 5,000 then 7,500, then 10,000 etc. This is exactly what I did to get to the 12.5 where I am now. I did it in 2.5k steps. ALWAYS use the same type / viscosity of oil, and ALWAYS pay the extra $10 for a TBN analysis. Also keep track of how much oil you add between changes, as the new oil affects the TBN and viscosity readings because the fresh oil contains fresh additives. TBN and viscosity are the primary indicators regarding "life" and suitable change intervals.
One last comment: Because of the HPOP reservoir, enough oil remains in the engine that it will affect results in the future sample, IF the viscosity or base stock oil is changed. I saw this when I went from 10/30 to the 15/40. Because the viscosity test is based on the viscosity of NEW oil, my numbers were too low for 15/40 on the first change after the switch. Subsequent tests were more consistent. If you want more accurate results on the next change, and you don't know what oil or viscosity is in it now so you can use the same, change the HPOP oil too. I would only bother to change the HPOP oil if you are really anal, or really want consistent results right off the bat. I didn't, and I don't feel it makes a ton of difference over time. But I bring it up because it does affect the first sample after a switch in oil type or viscosity.
Sorry for the TLDR. Perhaps you learned something.