Mileage is improving.

[Turbo Terry]

At 1600 miles my fuel mileage has seemed like it’s getting better. All winter driving no load or pulling. How long till break in 4000 miles ?

 

[nukegm]

comrade - my truck started to get better mileage and " woke up " at around 10k. have no idea if that is normal. cheers sir!

 

[Wiredawg]

Every Cummins I bought new has that magic 10K topping out... guess it gets "broke in" not Broken"

 

[Cummins12V98]

My 98 12V increased mileage up to 150k.

 

[Wiredawg]

Onliest (LoL) I ever saw a drop in mileage on any of them was about 1 to 1.5 mpg when "WE" went to ULS diesel fuel.

 

[slowmover]

My 98 12V increased mileage up to 150k.

My 3rd Gen CR 555 did the same.
Small, but it was there.

 

[slowmover]

At 1600 miles my fuel mileage has seemed like it’s getting better. All winter driving no load or pulling. How long till break in 4000 miles ?

Keep records. Every gallon, every mile and engine hours.

The overall average is what matters. Not tank by tank (prone to error) or season against season (summer vs winter) or solo versus towing (light vs heavy) as none of these are the true number. Only the annual average matters.

FUELLY App makes easy.
Graph TREND is how to read.

.

 

[Dave Zuber]

My 2001.5 didn't really free up until 50k miles. All the others had more and more burdens added, flat beds, canopy, weight.

 

[C M McCormick]

And I'm thinking it will even get better when they stop putting the additives in for the winter months..

Craig

 

[Turbo Terry]

Yes I can’t wait for some good old fashion number 2 diesel myself I have to use antigel. Don’t like it but it’s a must