Re: 7.3 oil change?
Our fleet uses Delo with lab oil testing. I can't say AMSOIL is any better than other synthetic but it's supposed to save you money by changing every 15K rather than the manufacture recommended times. I have yet to lengthen out my oil changes and don't plan to but twin filter systems are a key factor IMO, Amsoil or other aftermarket. I feel I should have gone with Mobile 1 syn after break in, but took the AMSOIL plunge. Unreal how different the engine ran after the switch. I don't know if the Mobile 1 is any better or worse, but probably cheaper.
BTW you need to run a cleanser before switching over to Amsoil.
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer
Sportsmobile 4X4 Adventures
..........On and off road adventures