1) I have no idea what ULSD is but I use the fuel at my local station and pay the applicable road/sales taxes.
No home heating oil with all it's algae going into my equipment.
2) Check: Always {After suitable warm up in winter) crank up the RPMs to 2000.
It'll help keep all the DPF equipment operating efficiently.
3) Air Filter cleaning...Check. Ya gotta be able to breathe!
4) I couldn't care less if the rewgen cycle is working when I complete my tasks.
It'll pick right up where you left off when you get back to work later, tomorrow or next week.
No matter.
5) If the "Limp Cycle" begins.....What I have done in the past, but this isn't in the manual, is: Shut the tractor down and restart.
In short... Reboot your onboard computer.
That'll sometimes help.
There....My 2 cents worth of advice
Oh, yeah. Don't forget to check for loose bolts (Even frame bolts)
I've caught some of those loosening over time.
Heck, I've had two of them shear right in half.
We work ours hard. Like it was meant to work.
Almost 800 hours now and it just sings.
Great tractor