Would you get it fixed?

DEF has nothing whatever to do with the DPF and the need or frequency of regenerations.

It’s like confusing tire pressures with the reason your radio works poorly.

DPF regeneration every 800 km or so sounds about right, recognizing that it is partly due to driving conditions and habits. Ditto DEF usage being partly due to conditions and habits. But neither influences the other at all.

Presume the truck is living an easy life for those conditions to exist. Don’t fix what ain’t broke.

carringb wrote:
Hitch up your trailer and go pull some hills....

The DPF is for catching particulates, formed when combustion temps are relatively low. Empty driving, especially in town and in cold weather, will never raise the combustion temps enough for a full burn, hence the DPF has to work extra hard.

DEF is used to react with Nitrous Oxides, which are formed under high combustion temps. You want to keep your truck running at these higher temps, because 1) It's more efficient and 2) It's easier to add more DEF than it is to clear soot out of the DPF.

So again.... Drive it good and hard to get it cleared up initially. And then try to change your driving cycle. I'm guessing you must do lots of short trips or idling now. You might come out way ahead in fuel $ and future maintenance headaches if you picked up a smaller car for in-town use.

This advice would be for a truck that is performing very frequent regens do to soot build up, but the op truck is the opposite and is going the full 500 miles in which the truck will then go to a forced regen which is ideal.

Hitch up your trailer and go pull some hills....

The DPF is for catching particulates, formed when combustion temps are relatively low. Empty driving, especially in town and in cold weather, will never raise the combustion temps enough for a full burn, hence the DPF has to work extra hard.

DEF is used to react with Nitrous Oxides, which are formed under high combustion temps. You want to keep your truck running at these higher temps, because 1) It's more efficient and 2) It's easier to add more DEF than it is to clear soot out of the DPF.

So again.... Drive it good and hard to get it cleared up initially. And then try to change your driving cycle. I'm guessing you must do lots of short trips or idling now. You might come out way ahead in fuel $ and future maintenance headaches if you picked up a smaller car for in-town use.

There's nothing to fix. Your truck is going to the max miles to a forced regen and as a result is using minimal def.

Your truck is performing text book so just enjoy the ride.

What about when the DEF in the tank goes bad and causes a problem. I wouldn't consider any malfunction a win, only a time delayed bomb.

I wouldn't bother getting it fixed. It will cost you time and probably fuel to drive to the dealer, get a ride home, ride back to the dealer, etc.
Plus, it sounds like it saves money on DEF too.
I'd call that a win.

Is the rig still under warranty/
Here is some interesting reading.
Service bulletin

Just another reason (one of many) that I have no desire to own anything post Tier 4 in a diesel engine. None of my farm tractors nor my pickup truck are Tier 4 compliant. No matter what brand of truck or farm tractor, they all share the same componentry, produced by the same manufacturers and when they fail (if not in warranty) it's always extremely expensive to repair.

I'll pass.