The most I've run on one oil change so far (since I installed the dual-remote bypass system) was just over 52,000 miles.
I changed the filters and topped off the oil about once a year/12,000 miles.
I changed it after 52,000 miles because it was SO black. But I sent in the oil analysis, and it came back good. It said I had a high soot level, change the filter and continue to use the oil. Too late, I already changed it!
I changed the oil again 39,000 miles later, when I didn't have an analysis kit handy, and I was in a hurry; then again 11,000 miles down the road when I went all out and flushed the trans, installed the Mag Hy-tec trans pan and Mag Hy-tec rear diff cover. I figured with 129,000 miles on the truck and the move from Colorado finished, I'd treat it to all fresh fluids.
I have one more of the "old" style bypass filters sitting on my shelf. After that one is gone, I'll switch to the new Donaldson oil filter (sold by Amsoil) which is supposed to do a BETTER job on the soot.
Oh yeah, I have over 146,000 on the truck now.