I used to have a 2002 F350 with the 7.3 as well. The 7.3 was in my opinion the best motor International made for these trucks. Mine only had about 131,000 when I got rid of it. Mechanically (Motor, Trans and Differentials) it ran great, loved the truck. The issue I had was the rust around the inner rear fenders, rocker panels and bottom of the inner doors. Had the rust fixed I thought but it returned a year or so later. I hated to get rid of the truck but because of the rust I had to.
When I had my 7.3, I thought the pol and filter were super easy to change. I used Delo 15w40, Shell Rotella 15w40 but mostly the Motor Craft 15w40 purchased at WM (3 Jugs in the 5 Quart Containers along with the Motor Craft FL1995 Oil Filter). The oil filter although pretty big was super easy to get to as you know. I would loosen it just a little then use a Sharpe Steel Punch to puncture the bottom of the oil filter to let the oil filter drain before removing it with no mess to deal with. The oil filter held well over a quart of oil as you know. Although the 7.3 held 15 Quarts of oil, it was a breeze to do the oil and filter changes. The Motor Craft 15w40 was/is a great oil as well. t was made for Ford by Conoco-Phillips specifically designed to work well with the HPOP ( High Pressure Oil Pump) that drive the Injectors in the 7.3 as the 7.3 was noted for sheering some brands of oil early on.
Looking back on it, I wouldn't have an issue using the Rotella T6 5w40 in the 7.3, it is really a good oil. I use the Rotella T6 5w40 in my 2011 Ram 3500 Cummins, no issues at all. As a matter of fact, I am the member of the Shell Rotella Website which allows you to cash in on Shell Products and other Merchandise on their website.
Much continued success with your 2002 F350 with the legendary 7.3, hang on to it as long as you can.