Good point by Zanzabar, because there might have been a Potassium compound in the factory fill as some break in oils or some light greases used during engine assembly are different to normal engine oils.
One difficulty with interpreting UOA results is that if you don't know exactly what was in the engine before you started an oil analysis program and what the virgin oil analysis is, then it can get confusing.
How do the wear metal results compare with other results for the same engine, as they seem too high to me?
Lower viscosity oils flow around the block faster when hot and just because they might offer slightly less protection when hot, does not mean they will produce less engine wear. Local hot spots can increase it in some engines, so as this engine seems to be approved for both 5/30 and 5/40, it would be best to ask on a VW forum which viscosity is best. In addition I would definitely ask a VW dealer what type of oil should be used and if a Zinc additive is recommended.
The real interesting point is the low TBN in some ways, as most VW TDI's seem to suffer from cam wear issues to some degree and it would be interesting to see if cutting the OCI to 5,000 miles solves the problem. The TDI oil filter is rated for 30K km oil changes as far as I can tell from the LM oil guide, so it would be better to do alternate service filter changes to take advantage of the filtration efficiency increase that occurs with moderately dirty filters.
Originally Posted By: zanzabar
The potassium is probably just remnant of some break-in issue, the fact that it's trending down is good.
All metals other than iron are looking fine and totally normal for break-in wear. It takes 50-100k for a TDI to 'break in', so high iron and to a lesser extent some of the other metals are not really worth worrying about.
With that said though, that upward spike in iron is troubling and I'm VERY suspicious of this 5w30 oil. It is almost certainly linked to the premature cam wear in the PD TDIs and I suspect it is not optimal for the later models either. Move to a different oil: Mobil1 ESP Formula M 5w40. The dealers have it you probably just have to request it. That or any other reputable 5-40 diesel oil that meets the VW 505.01/507 spec (there are many, the important part is that it's a 40wt).