X2-
I have always wanted to and finally did an oil analysis. There is no way of knowing exactly the condition of your oil without one. I drive a 7.3L powerstroke DD and I interval the change at 5000 miles. I use Mobil Delvac 1300 and they recommended I extended to 7500 miles. The traditional OCI is just a recommendation.
I do not drive my Inline 250 turbo enough to actually analyze it. I just change it once a year.
If you have not been to the site, Bob Is The Oil Guy, google it and get ready to be informed.
Boucher'
