Do you have a bypass oil filter? I would guess that the original owner didn't .... Ford dealerships seem to hate all aftermarket mods!
Nope all stock but always used Ford filters. I had a by-pass on my 7.3 and all my oil analysis came back w/ really low numbers.
On the 6.0/6.4 IIRC Ford sold the patent rights to only a few companies, one being Fram and I've seen the patent # on just one other. And as Jon from Little Power Shop indicated in a sticky, the oil filter size is very specific thus issues can arise from aftermarket due to avoiding patent right infringement.
I installed a Bosch on the 6.0 right after I got it and I had all the issues Jon was mentioning. I took the filter housing off and low and behold the Bosch top had torn off. It was obviously a hair too large as it appeared to have compressed while simultaneously tearing. Either way, Bosch paid for a top end tear down and inspection. I got all new orings, gaskets, stand plugs etc. Thankfully I had less than 500 local hwy miles on that filter.
Back on task, my experience w/ Ford is a majority of them are either stupid or play the voided warranty card. I found 1 dealership that took care of all my issues and even installed my dee-leets. After I drove the 08 hard and blew the gaskets, the mechanic also discovered the heads were cracked and the shop manager had Ford warranty the heads. It took 2 sets to get it done but thats a whole other story.
IMHO If you're really wanting a bypass locate some good DIY threads using HQ bypass filters. I like the bypass options that use Donaldson, Baldwin bypass filters, etc.. If you're ever in a pinch you can almost always find the filters at a local class 8 dealer, truck stop or farm fleet/john deer type dealer.
You can get the tapped filter top and oil fill return from LPS, I have a set and they are on sale every once in awhile. There may even be some redneck cnc'd aluminum options on fleabay as well.
Good luck!