On the big rigs with the Frantz elements for the LuberFiner 750 filter housings, we were changing filters at 10K mile intervals, and never changing the crankcase oil. Some engines had 80K or more on the oil, and it was still passing a spectrometric sample test. Of course, the crankcase capacity was 10 gallons, and we added 1 1/2 gallons to top off after the filter change.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!