10k is a cake walk for syn oil, analysis always says mine is still good but I still dump it at 10K, I do a filter at 5k too. I am concerened with the amount of soot that doesnt get picked up by the filters, I currently run an Amsoil BE-100 (I think)slip stream and I know it is filtering my oil down to 2 micron but I can turn new oil black within a few hundred miles. I have read that the toiltpaper filters will take the soot out, I think this would be good to install upstream of my pollish filter that way if any paper were to get loose the pollish filter would trap it.
Cheers, Kevin