How Much DEF Are You Using In Miles?

[DeansRedRam]

In the last 3000 miles I still have just under 3/4 tank of DEF. I have towed 13k for about 80 of those miles and probably 2000 of those 3000 miles are highway.
Truck sips DEF. Although I heard that while towing, drinks alot.

 

[kthaxton]

In the last 3000 miles I still have just under 3/4 tank of DEF. I have towed 13k for about 80 of those miles and probably 2000 of those 3000 miles are highway.
Truck sips DEF. Although I heard that while towing, drinks alot.

Keep in mind, the first 1/2 of the DEF gauge travel is not accurate....it is estimated. The last half of the tank (per the gauge) will go much quicker.

 

[gsbrockman]

Decided I’d update this thread with some up to date information.....

Through 68,722 miles, White Lightning has consumed 144.301 gallons and $405.93 dollars of DEF.

This equates to

• 476.24 average mpg
• $2.813 average cost per gallon
• $0.0059068 per mile
• $5.91 per 1,000 miles (much easier to comprehend)

And yet another update.....

Through 215,762 miles, White Lightning has consumed 514.586 gallons and $1,452.33 dollars of DEF.

This equates to

• 419.29 average mpg of DEF
• $2.822 average cost per gallon
• $0.0067311 per mile
• $6.73 per 1,000 miles

20,813 gallons and $56,448.31 of #2 has been consumed.....and the DEF rate is 2.4724%. Lifetime #2 mpg is 10.36 mpg.

 

[AKDoug]

2019 CC 3500 SRW H.O. 5500 mile trip, running speeds from 50mph to 75mph, 61mph average, 1/2 with 1000# of cargo in bed, half with same 1000# in bed and 6500# gooseneck in tow, used 13 gallons of D.E.F. 423 miles per gallon. Oddly enough, almost dead on White Lightning's number.

 

[AH64ID]

2019 CC 3500 SRW H.O. 5500 mile trip, running speeds from 50mph to 75mph, 61mph average, 1/2 with 1000# of cargo in bed, half with same 1000# in bed and 6500# gooseneck in tow, used 13 gallons of D.E.F. 423 miles per gallon. Oddly enough, almost dead on White Lightning's number.

How much #2 did you use?

 

[AKDoug]

How much #2 did you use?

We're still on a #1/#2 mix in the great white north. Thank goodness since it was below 0F several times on the trip. I burned 401 gallons on the trip. 3.25% DEF to fuel which is higher than White Lightnings. I have not had the latest recall update, so I think my consumption will go down after that.

 

[AH64ID]

We're still on a #1/#2 mix in the great white north. Thank goodness since it was below 0F several times on the trip. I burned 401 gallons on the trip. 3.25% DEF to fuel which is higher than White Lightnings. I have not had the latest recall update, so I think my consumption will go down after that.

That’s a lot of DEF. I’ve heard the new motors use more, but that’s shocking. My highest %age so far is 2.1%, with a 1.8% life average. 13.2mpg life avg.

Hopefully the update helps you.

 

[TFucili]

My buddy has an earlier build '19 3500 SRW, and it was ferociously gulping DEF. Re-flash did help. He is a few re-flashes behind, though. Has some serious "chuffing" and stalling on cold starts at elevation.

 

[AKDoug]

That’s a lot of DEF. I’ve heard the new motors use more, but that’s shocking. My highest %age so far is 2.1%, with a 1.8% life average. 13.2mpg life avg.

Hopefully the update helps you.

My usage doing short runs this winter was nothing like this. I was caught off guard and ended up buying 5 gallons worth on the road. I fully expected to only use 8 gallons.

 

[HPSimpson]

My 2014 3500 appropriately 11k towing 28 Parker boat, doesn't use nearly as much has 2019 2500 on trip down to southern Ca nearly 3.75 gallons towing 4k rigid inflatable boat. I have been back to dealer an was told this is normal usage?Is this really.

 

[R.Taylor]

In my 6000 miles I've burned roughly two and a half tanks of DEF. But I also have been using OptiLube XPD since day one. I read that it may lead to more DEF use and regens but then I like knowing my CP4 is lubricated. I also have a lead foot and am generally moving along around 80mph if I'm not towing. I have a reverse commute to my shop from home so the roads are empty . I have not had any flashes or updates or recalls done since delivery in Nov 2019... Only the OTA update for the Uconnect 12".

 

[AH64ID]

I've topped off twice this month and thought I'd update my info. Both filled at the pump. Same trailer on all the towing so the weight was generally ~20K GCW.

The first top off was in preparation for a family camping/road trip.

Miles: 3004
Hours: 107
Gallons of DEF: 2.965
MPG DEF: 1013
Average DEF GPH: 0.028
Gallons of Diesel: 220
MPG Diesel: 13.7
Average Diesel GPH: 2.1
% DEF:Fuel: 1.3% (lowest yet)
Towing miles: 724/24%

I then topped off today after the road trip to see what my usage was.

Miles: 2144
Gallons of DEF: 4.024
MPG DEF: 533
Average DEF GPH: 0.073
Gallons of Diesel: 192.7
MPG Diesel: 11.1
Average GPH Diesel: 3.5
% DEF:Fuel: 2.1% (tied for highest)
Towing miles: 1642/77%


I was initially surprised at the difference, but it's the added towing and much higher average GPH making more NOx.

Since I bought it
Miles: 17,805
Gallons of DEF: 23.778
MPG DEF: 748.8
Gallons of Diesel: 1377.5
MPG Diesel: 12.9
%DEF:Fuel: 1.7%
Towing miles: 5948/33.5%

 

[J VanSteenwyk]

DEF usage is directly related to fuel consumption. Engine manufacturers plan 2-3% DEF per gallon of diesel depending on vehicle operation, duty cycles, geography, elevation, load, etc. I plan 2% solo and 3% when towing. It can get as low as 1% based on those factors and driving conservatively.

 

[slowmover]

DEF usage is directly related to fuel consumption. Engine manufacturers plan 2-3% DEF per gallon of diesel depending on vehicle operation, duty cycles, geography, elevation, load, etc. I plan 2% solo and 3% when towing. It can get as low as 1% based on those factors and driving conservatively.

Generally.

Specifically, highest consumption will have the most to do with being OUTSIDE engine design parameters.

The engine being worked per design specification (is lowest consumption); where factors of load, road, elevation, temperatures all meet.

Extended idle will burn an unreal amount of DEF (in comparison).

It IS accurate to look at engine life being total gallons consumed. Miles/Age don’t factor near as closely.

Idle percentage has to be under 10% one wants economical operation. That’s gallons-per-hour AND miles-per-gallon of diesel.

Once that’s accomplished (no more childishness), then DEF use comes clear.

There’s an overall average to DEF usage factored as “normal”. Understanding the specifics is the key to unlock.

 

[Newsa]

Extended idle will burn an unreal amount of DEF (in comparison).

Idle percentage has to be under 10% one wants economical operation. That’s gallons-per-hour AND miles-per-gallon of diesel.
.

Why would the exhaust need more DEF when the exhaust is too cool to produce NOx at idle?

Do you mean the idle hours (percentage)? Probably not many have 10% idle hours. I think it was SAG2 who mentioned in another thread that as long as you have all the flashes, you can idle all day provided ambient Temps are above freezing?

 

[slowmover]

I've topped off twice this month and thought I'd update my info. Both filled at the pump. Same trailer on all the towing so the weight was generally ~20K GCW.

The first top off was in preparation for a family camping/road trip.

Miles: 3004
Hours: 107
Gallons of DEF: 2.965
MPG DEF: 1013
Average DEF GPH: 0.028
Gallons of Diesel: 220
MPG Diesel: 13.7
Average Diesel GPH: 2.1
% DEF:Fuel: 1.3% (lowest yet)
Towing miles: 724/24%

I then topped off today after the road trip to see what my usage was.

Miles: 2144
Gallons of DEF: 4.024
MPG DEF: 533
Average DEF GPH: 0.073
Gallons of Diesel: 192.7
MPG Diesel: 11.1
Average GPH Diesel: 3.5
% DEF:Fuel: 2.1% (tied for highest)
Towing miles: 1642/77%


I was initially surprised at the difference, but it's the added towing and much higher average GPH making more NOx.

Since I bought it
Miles: 17,805
Gallons of DEF: 23.778
MPG DEF: 748.8
Gallons of Diesel: 1377.5
MPG Diesel: 12.9
%DEF:Fuel: 1.7%
Towing miles: 5948/33.5%

It’s not blanket. One need a count of accel & decel events. (Slight throttle changes not in contention). Entering a highway. Climbing a grade. Slowing for construction. Exiting.

Understanding that ANY on-highway brake use (besides downgrade & marked curves) is poor skill; brakes effectively burn a huge amount of fuel.

Same for steering corrections. (This is all Fuel Economy stuff). Number of steering corrections per 100-miles is a factor.

(This post is about standing in those shoes. Not about the man wrote it).

Friend, the test is to run the pickup over some of the same course (unhitched) but otherwise carries the same load (Scale it). Same speed and cautions at the wheel (AS IF you were hitched). 200-miles round trip should do it.

Travel trailer fuel burn penalty is 40% as an average 1970 or 2020. Aerodynamic. The added weight is an emotional problem. RVers ain’t at all capable of sorting the mechanical from that (you are).

An FE test where cruise control is allowed to be The Drivetrain Manager sorts the differences in a way you’d appreciate.

I can run 30k in the box — and on some of the most difficult U.S. Interstate terrain — let the cruise + engine brake control the speed with virtually no input from me.

Doing it again (same settings) while empty means (mainly) a higher average MPH.

The DEF burn rate doesn’t change as much as the fuel consumption rate. It doesn’t change much at all. They simply don’t track each other when the engine is in or near design specs.

Granted, these things (tests & observations) are easier in commercial work at 10,000-miles/month.

Engine demand has to be removed from poor driver skill.

But the start till has to be the control of idle time percentage of total engine hours. Without that, your figures are missing THE crucial number.

Big truck fleet spec won’t allow more than a few minutes of idle time. At all. Unless outdoor ambient temps are very high. At 1.25-gals/hr diesel consumption (coolant + oil temps kept above 150F), DEF consumption goes thru the roof.

If you establish a low year-round idle time percentage (no such thing as “winter fuel”; energetic content change is under 5%) then your other recorded numbers have some meaning where you’ve also reckoned Aero + Weight changes via drivetrain consistency (computer control of speed).

DEF, (granted), so what? It’s another peek at computer-control. You haven’t believed me in years past re FE or hitch-rigging to make your own tests (this stuff is simple), so here’s another chance.

With respect, were I to decide to employ MAD programming with my CTD, why would I wish to engage your services as it’d be analogous to hiring someone without big truck experience to program that vehicle?

I’m only trying to say that there are insights arising from testing — and changing driver habits to incorporate them — that can’t be obtained otherwise.

I get a good laugh out of guys who disbelieve my MPG numbers thinking I only run slower.

DEF Burn IS a marker. But not when the operator wanders on & off the reservation. He doesn’t know the map boundaries.

Scale that combined rig one day, will ya? (I’ve posted The Three Pass Scale Method elsewhere). There’s a sweet spot (range) for weight that getting past that changes things. It’s more the truck than the trailer weight. Understanding what changes the travel trailer brings ISN'T much about it’s weight.

It’s the operator being highlighted.

The action to take himself OUT of that equation brings results.

.




.

 

[slowmover]

Why would the exhaust need more DEF when the exhaust is too cool to produce NOx at idle?

Do you mean the idle hours (percentage)? Probably not many have 10% idle hours. I think it was SAG2 who mentioned in another thread that as long as you have all the flashes, you can idle all day provided ambient Temps are above freezing?

Big trucks versus pickups aren’t totally comparable. Pickups are disposable. Price wouldn’t cover engine + trans for a big truck.

Sure, one can idle almost anything. It’s a penalty in life and reliability. Always has been. Emissions are what change the warnings.

There’s ZERO reason to have high idle times (above 10%). It’s an emotional problem.

.

 

[slowmover]

I’ve noted before that diesel-engine pickups went from being a fine idea to being a bust.

Until 2006 with:

1). Diesel priced lower than gasoline; and,
2). emissions-controls being minimal,

the cost-benefit ratio favored the owner who had a plan detailed in using it as a work vehicle (income-producing or off-setting) with high annual average miles.

That’s gone. And it wasn’t an enormous advantage at any rate. It was in in marginal returns.

Gas engines are night-and-day better today than in 1998. Diesels, barely any.

Everyone else (then and now) weren’t going to be bothered to learn how to use vehicle capabilities. “Panties-twisted”, stuff.

Take a pass on the basics of operation Daddy shoulda taught ‘em.

Cry, boo hoo, you bring it up.

The tee shirt, tattoos & TV crowd.
(Getcher mask on!)

.

 

[gsbrockman]

Gas engines are night-and-day better today than in 1998. Diesels, barely any.

The gas engine comment is true, but it still doesn’t mean that [for those of us that actually use a diesel truck] a gas engine is always a viable alternative (read GVWR and/or GCWR) for lots of us.

 

[TFucili]

The gas engine comment is true, but it still doesn’t mean that [for those of us that actually use a diesel truck] a gas engine is always a viable alternative (read GVWR and/or GCWR) for lots of us.

And exhaust brake.