Currently in town here, $3.20 for Gasoline, $3.43 for diesel. So a 7.19% upcharge for diesel. That is the closest I've seen it in a long time.
At that delta, you have to put 117,247.49 miles on to recoup the $12,000 upcharge to go with the diesel.
If you go with a 20% difference, which is I believe to be more normal around here (but I could be wrong), that return goes out to 219,638.67 miles. And I know I've seen 30%, most of our fuel goes to Ag and when they get busy, it goes up in price horrifically. But that could be a regional issue.
I had to change two fuel filters at every oil change on my Fiat RAM RAM, and three gallons of oil + oil filter. It was $200 for me to do it. I ran good Fleetguard filters, and Delvac in both my Fiat and my Dodge. The Dodge had a aftermarket lift pump on it though, and that filter really only needed to be changed every 50k miles or so. They usually got swapped soon as they would rust and look like crap.
9.8 was my lifetime average on the last one. That average is made up with 84% of the miles, (mostly with a an enclosed trailer), on the ball and pretty much minimum 10k pounds. Max with that trailer I'm about 13,500.
My pickups get used. They rarely get driven unless there's some strange reason. I hate paying for the POS. That ford I've got now had 100 miles on it and I had to run to western colorado. I took the turdwagon 80 instead.

I also didn't want to break a new engine in droning down the interstate for 36 hours.
and 2800 rpm is ripping for peak torque. That's about where it started to do something on my Fiat too. Same problem with the R2.8. Gotta ring it out before it'll fuel to get cylinder temps up for a cleaner burn.
I think my 01 was about 1750 stock. With programming, a load, and abusive throttle, it would fuel so hard down at 1200 rpm you could hear the pilot bearing getting angry. (probably because it was trying to break off the input shaft....) Clutch would shudder every so slightly too.