Regular oil like Rotella I say 3000-3500 miles, Amsoil synthetic with the dual bypass filter system I’d guess at 20,000. I tried Amsoil with the factory filter system and it still gets pretty black and dirty looking in less than 100 miles so I couldn’t make myself go more than 6,000 or so before I couldn’t stand it and had to change. I’m thinking of getting the dual bypass system and trying it again. A engine can cost from $8,000 to $12,000 and injectors from $2000-$3000 not to mention labor and down time, oil is cheap in comparison but from what I have seen the crappy factory air intake will ruin the engine a lot quicker than oil.