Problem typically isn't engine contaminants in the oil, it's sillica content, meaning dirt getting into the oil sump from various locations through the engine (poor seals, etc).

There are oil test kits where you can go 10k and take a test. My buddy did it with his diesel and in our area the silica was just too high after 10k, so I've just gone with his study rather than pay $$ for my own test.

And all filters have a pretty liberal bypass valve (so that a clogged filter won't blow up your engine), so I'm unsure how much effective filtration is really going on anyway.

So I just roll with 10k or I go by what the vehicle says if it is tuned for sythetic.