DEF usage?
Lead Driver
Joined: Nov 2005
Posts: 8,466
Likes: 4,962
Are you sure it was 7.5 gallons of DEF in 1900 miles???
Mine is probably using half that much.
Cargo Master
Joined: Oct 2019
Posts: 2,836
Likes: 1,191
From: Southeast MO
I know I read somewhere that the 2020+ 6.7 trucks use less EGR and more DEF to control NOX compared to the previous years which used more EGR. I'll gladly take this trade off. I'll try to find the article.
New User
Joined: Sep 2021
Posts: 5
Likes: 0
From: Canada
Def usage in my 18 PS
Iv just added def to my tank for the first time sense owning this truck. I purchased it new and seems to use very little def
Lead Driver
Joined: Nov 2005
Posts: 5,229
Likes: 4,245
From: Kaysville Utah
The 2020 and newer have steel pistons and run a lot hotter than my previous trucks. I mean, I never saw 1350° when towing up a grade in my 2015 or 2017 trucks. But I see it pretty common in my2020 truck.
Hotter combustion temps mean more NOx and that means more DEF.
I got more HP, get better fuel mileage, at the cost of alittle more DEF. It's a good truck off as far as I'm concerned. DEF is still cheaper than diesel
Hotter combustion temps mean more NOx and that means more DEF.
I got more HP, get better fuel mileage, at the cost of alittle more DEF. It's a good truck off as far as I'm concerned. DEF is still cheaper than diesel
5th Wheeling
Joined: Jul 2021
Posts: 38
Likes: 16
The 2020 and newer have steel pistons and run a lot hotter than my previous trucks. I mean, I never saw 1350° when towing up a grade in my 2015 or 2017 trucks. But I see it pretty common in my2020 truck.
Hotter combustion temps mean more NOx and that means more DEF.
I got more HP, get better fuel mileage, at the cost of alittle more DEF. It's a good truck off as far as I'm concerned. DEF is still cheaper than diesel
Hotter combustion temps mean more NOx and that means more DEF.
I got more HP, get better fuel mileage, at the cost of alittle more DEF. It's a good truck off as far as I'm concerned. DEF is still cheaper than diesel
5th Wheeling
Joined: Sep 2020
Posts: 26
Likes: 8
Wow! Glad I came across this thread, thought something was wrong with my truck (2020 HCTT, CC, SB). To the extent that I called my selling dealer and inquired if it was possible for the truck to get stuck in re-gen mode. They said no, not possible. I conventionally tow a bit lighter than most, ~7k Lbs. and see mpg's from mid 15's to low 16's. But on a recent trip towing (one way) from just west of Detroit to Indianapolis it used a tank of fuel and half a tank of DEF. I don't feel so worried now.
Cargo Master
Joined: Oct 2019
Posts: 2,836
Likes: 1,191
From: Southeast MO
Wow! Glad I came across this thread, thought something was wrong with my truck (2020 HCTT, CC, SB). To the extent that I called my selling dealer and inquired if it was possible for the truck to get stuck in re-gen mode. They said no, not possible. I conventionally tow a bit lighter than most, ~7k Lbs. and see mpg's from mid 15's to low 16's. But on a recent trip towing (one way) from just west of Detroit to Indianapolis it used a tank of fuel and half a tank of DEF. I don't feel so worried now.
DEF usage and regen's are not related.
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Cargo Master
Joined: Oct 2019
Posts: 2,836
Likes: 1,191
From: Southeast MO
Well it uses less diesel but not sure if it is cheaper than diesel. I was on a trip and needed some and ended up paying ~$17 for one of the boxes which I think are 2.5 gals. Now that I realize I am going to use more I will top off more frequently at truck stops as I think I paid ~$3/gal at the pump. I remember when it first came out was supposed to fill DEF about every oil change, well we are way more often than that.
Lead Driver
Joined: Nov 2005
Posts: 8,466
Likes: 4,962
When comparing DEF prices between jugs and the pump at a truck stop, don't forget to add sales tax on those jugs, it is built into the pump price.
I have been buying jugs at walmart, but they just recently went up on the price by a dollar, so now it costs more than at the pump after tax is added to the jug price.
I have been buying jugs at walmart, but they just recently went up on the price by a dollar, so now it costs more than at the pump after tax is added to the jug price.
Lead Driver
Joined: Nov 2005
Posts: 5,229
Likes: 4,245
From: Kaysville Utah
True.
DEF consumption is related to High Combustion temps that cause NOx.
So the hotter your combustion, The more DEF you will use.
Combustion temps will climb pretty much any time your turbo is creating boost.
And the '20 and newer 6.7L engines seem to be running 150° hotter than my previous trucks.
DEF consumption is related to High Combustion temps that cause NOx.
So the hotter your combustion, The more DEF you will use.
Combustion temps will climb pretty much any time your turbo is creating boost.
And the '20 and newer 6.7L engines seem to be running 150° hotter than my previous trucks.
Cargo Master
Joined: Jul 2009
Posts: 2,710
Likes: 77
From: Central Florida
I'm glad I saw this thread. People I've talked to at the campgrounds keep telling me how little DEF they use. Towing our 41' Montana 5th wheel we use a lot of DEF. I learned the hard way, to keep 4 jugs available when towing. This past February (peak COVID times) we went down to Florida and out west. On the way down to Florida there was some sort of DEF shortage. At one point we were limited to 50 mph. When I finally found a place to buy DEF they only had 1 box which we paid $30 for the 2.5 gallons. Every time we stopped we looked for DEF, very few places had it. Very few truck stops would sell us any because the truckers needed it. The whole rest of the trip if I saw DEF on the shelf, I bought it. I bought so much DEF that I still have 3 boxes in my garage 
