DEF usage

Normal for what?

How large is the tank? Most mfg's have different tank size options. Give us some hard numbers in terms of DEF MPG so we have something to work with.

 

DEF usage

Sounds like you're right in the range at 118 MPG on DEF. Newer engines are using more DEF because of NOx reduction targets on newer engines.

 

Def usage is tied to nox which goes up when cylinder pressures rise aka bucking wind , hard on the fuel, heavy loads at higher speeds. Whenever higher horsepower is needed it uses more def.

 

4-5 gallons,500 miles,2023 X15,565 hp.
165,000 lbs 65 mph.

 

My habbit was to fill-up DEF about every third fuel fill-up. Every fuel purchase for me was a fill-up. So I'd estimate 1000-1500 miles between DEF top-off. I usually had 1/4 or more DEF remaining when I added to it.

 

Mine is 1 deff fill up to 3 diesel fill ups…. I used to have high def usage some time ago.. had def fluid filter replaced, found a crack by the doser annd had it welded. also replaced the doser injector. I think your usage is normal.