I don't waste money on oil analysis myself, however I should one day just to see what I have deep down in that there fill hole...
My lil Accord gets 7500 on conventional, so I feel comfortable even on the cheep synthetics to run 10k OCI's. I in fact try to give myself some room for oil change by running the EP type oils during the colder months, I have no problem pushing Edge or Mobil 1 EP oils out to 15k if need be, however most of the time they get changed around 13k weather permitting of course. So my point is the type of car you drive, oil sump capacity, and many other things do play a part in your OCI, that's why the manufactures vary so much when they state the specified/recommended OCI. I would first check the manufacture OCI, then you could be the judge yourself if a synthetic can extend your OCI out to 10k