I use Used Oil Analysis (UOA) to initially set my oil change interval (OCI) for a particular oil. You will need to ask for a Total Base Number (TBN) with the analysis which will cost an extra $10 over the approx. $20 analysis fee. I don't know if you can just buy a TBN or not. I believe a TBN of greater than 2 means there's still contaminate fighting additives in the oil. In my last analysis Blackstone advised I could go to 7k OCI from 6k, but 6k equals about 1 year OCI which I'm happy with.

For some idea of filter condition the "Soot" concentration in the analysis will tell you how well the filter is doing it's job. I believe better filtration trumps oil make choice. Once my OCI is set I do once per year analysis (no TBN) to see if any anti-freeze/excessive fuel is in the oil and what the used oil properties are compared to new. Frankly if I'd see excessive wear metals in the analysis I don't know what I'd do, other than a rebuild. If the engine was running OK with good compression and no/little oil consumption then you might as well drive it for now no matter the wear, unless you want to unload it on the next guy to fix, but I'll leave that to your own conscience.