This UOA is good for a 3.5L EB; the wear rates are admirable. If you're happy with the results, I'd stick to the plan. I think it's certainly possible to extend the OCI a bit; try 8k and see what the UOA tells you.
Kschachn is right, but I'd like to refine the point made ...
As for the topic of UOA data and how to interpret it, I think some of you need to visit (or revisit) this:
Reviewing UOA Data Used oil analyses (UOAs) are tools. And like most tools, they can either be properly used or misused, depending upon the application, the user, the surrounding conditions, etc.= There are already many good articles and publications in existence that tell us how to interpret...
bobistheoilguy.com
You most certainly can use UOAs to compare/contrast lubes. But, and
this is a huge caveat to understand, you
cannot accurately do so with only a single or a few UOAs. To be statistically viable, you need a bare minimum of 30 sample of each; 30 of lube A and 30 of lube B. At 5k mile OCIs, you'd need 300k miles of driving to just review two lubes, one relative to the other.
IT IS COMPLETELY IMPROPER TO THINK YOU CAN MAKE INFORMED DECISIONS WITH LESS DATA. You cannot understand the real normal variation (std dev) with low sizes of sample sets.
It is imperative to understand the difference between micro data and macro data.
You can compare/contrast your single UOA to macro data; how does your engine and lube stack up against a group average? You essentially can say "my engine and lube are behaving normally, as they are within the statistical bounds of macro standard deviation". But you cannot say "my engine or lube are better or worse" without having enough data to understand the normal variation, and that only comes with large sample sets of micro data.
I realize it takes all the fun out of this; it makes BITOG a lot less exciting. But you all are fooling yourselves, to your own detriment, if you think you can make a decision regarding any one lube being better or worse than another with only a few UOAs.
