Jump to content

DEF Usage…..

mark1968
 Share

Recommended Posts

mark1968 Enthusiast

mark1968

Posted
Posted

So we were fortunate to buy one of the new 3.0 diesels in early 2020. We enjoyed that GMC denali for the last few years but with all our long distance driving between our kids/home, it was reaching 100k miles and I read great things about the updated 3.0 (LZ0) and decided to trade in our 2020 and get a 2024 ZR2 Bison with the 3.0.  

For the last week we have been breaking the new truck in and driving across country.  We were very used to the DEF usage on our 2020 and with a 1000mile trip we’d normally (not towing) see about 2 blips down on the DEF guage.  However with the new truck, we are seeing significantly more DEF usage on basically the same trip (more than half way down) so we are kind of surprised.   I know Ive read of other owners who had the original 3.0 diesels engine and traded up to the new LZ0 one, so what has been your experience?  Love to hear feedback?? Thanks!

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

I don't have first hand experience with the diesel but some food for thought is that the emissions standards between 2020 and 2024 are possibly different and or that GM is a little ahead of the curve for changing standards and they want to meet those new requirements. So that way they stay compliant in the states that really crack down on testing. Also the ZR2 bison will make the truck work harder to do the same thing compared to your old truck. A lifted truck with heavy duty tires is causing more DEF usage.

newdude Senior Enthusiast

newdude

Posted
Posted
2 hours ago, mark1968 said:

So we were fortunate to buy one of the new 3.0 diesels in early 2020. We enjoyed that GMC denali for the last few years but with all our long distance driving between our kids/home, it was reaching 100k miles and I read great things about the updated 3.0 (LZ0) and decided to trade in our 2020 and get a 2024 ZR2 Bison with the 3.0.  

For the last week we have been breaking the new truck in and driving across country.  We were very used to the DEF usage on our 2020 and with a 1000mile trip we’d normally (not towing) see about 2 blips down on the DEF guage.  However with the new truck, we are seeing significantly more DEF usage on basically the same trip (more than half way down) so we are kind of surprised.   I know Ive read of other owners who had the original 3.0 diesels engine and traded up to the new LZ0 one, so what has been your experience?  Love to hear feedback?? Thanks!

 

 

GM has an updated info bulletin about DEF usage on 2020-up trucks. 

 

READ HERE  - Unable to Fill the DEF Tank – TechLink

 

TLDR, don't add DEF until you see the countdown warning for "65MPH soon".  The algorithms are always changing the amount of DEF used based on fuel consumption.  

 

AND HERE - Diesel Exhaust Fluid Consumption – TechLink

 

The DEF dosing strategy will increase DEF injection when working the engine hard, especially during towing or high payload situations.  Also see ever changing emissions requirements.  Also, you now have a ZR2 Bison which is much less aerodynamic and fuel efficient than your 2020 Denali was which means increased DEF usage even when empty because lower MPG.  

 

 

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)

I had a '21 LM2 and now a'23 LZO

 

I don't put much faith in estimating def usage per segment.

 

All def added as been from a metered pump, and when def is added the tank gets filled so I can do def mileage calcs the same way as fuel mpg. 

 

The truck is using def at the expected rate of 2% of fuel (2 gal def per 100 gal fuel). The older truck, and the 6.6's I ran before were all very close to the 2% of fuel usage rate.

 

Lifetime average currently 1380 miles per gallon. (first 24,734 miles)

image.png.c7ae13bbe7c4248f7559dde1683edb66.png

 

 

My question would be how does the fuel economy / fuel used during the trip compare with the previous truck? 

It it used more fuel -- speed, headwind, ac running hard due to highe temps, etc -- then it should use more def.  

 

 

 

Edited by redwngr
mark1968 Enthusiast

mark1968

Posted
  • Author
Posted

I really appreciate the comments!   I was also thinking that the ZR2 Bison is heavier than the Denali and less aerodynamic so that could be part the difference.. On our normal round trip run of about 2k miles, on the old Denali we would get about 24 mpg.. On this trip we just finished we got about 21 mpg.. I expected lower mpg due to the lift but had not considered a big DEF difference.. I guess ill keep monitoring and see if it is around the 2% of fuel usage.  As a side note, we do love the truck.. it is a beast and more suited to the remote area we live in now..

 

What’s interesting is our son also just bought a Trail Boss with the new 3.0 and I drove it back to East Coast for him. Even with the lift i didnt see the level of DEF usage we saw on this trip with the ZR2.  So there must be a factor of weight and we did have some headwinds coming West yesterday.. Anyway, thanks again for everyone’s thoughts!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • newdude
      2027 GMC Sierra: Official Discussion

      By newdude · Posted

      Follows the motif on the Sierra EV.  Satin finsh to the lower bumper area, painted above:   Elevation       Denali      
    • taze
      I love my truck but

      By taze · Posted

      Not exactly what I was hoping for, but I do like it. I wonder if they'll bring back Smokey Quartz Metallic? 🤔 https://gmauthority.com/blog/2026/06/here-is-the-all-new-2027-gmc-sierra-1500/
    • tjonesdfw
      2027 GMC Sierra: Official Discussion

      By tjonesdfw · Posted

      Whoever greenlighted the work truck matte black front bumpers on every trim but the AT4X should be fired!  I was hoping that was an AI mistake, but just realized they were on every model of the 2027 Silverado too.     Some parts of the interior do look premium, but the Denali Ultimate dashboard looks like an afterthought.  At least they appear to have lost the microfiber the high end Silverado models showed, but the '27 High Country dash looks better than the Denali.  
    • bluev8
      Intermittent no-code issues on 2022.5+ V8 trucks — what did the shop fail to capture?

      By bluev8 · Posted

      New member here. I am researching a read-first event-recorder concept for late-model GM V8 trucks. This is not a sales post. There is no product link, price, preorder, or mailing list. I am trying to determine whether the underlying problem is real before building anything.   Has your truck ever had a brief problem such as: - rough running or a momentary misfire - an oil-pressure warning or unusual pressure event - reduced power or a brief stall - a U-code or lost-communication problem - a symptom that disappeared before the dealer or independent shop could reproduce it   If so, I would appreciate the following details: - year, model, engine, and mileage - what happened and under what conditions - whether a DTC and useful freeze-frame data were stored - whether the shop was able to reproduce it - what the eventual confirmed repair was, if known - what additional information would have helped the diagnosis   The concept being evaluated is a removable leave-in recorder that continuously retains a rolling window from before and after an event. It would not tune, reflash, clear codes, or change the vehicle calibration.   I am also not claiming that it could predict lifter failure or see every internal ECM variable.   The real question is whether continuous event history would add enough useful evidence beyond freeze frame, GDS2, and existing scan tools — or whether it would simply be another unnecessary gadget.   For owners and technicians, which problem would make something like this genuinely useful: 1. intermittent misfire or AFM/DFM-related behavior 2. oil-pressure events 3. lost communication or electrical faults 4. none of the above Please be blunt. Negative feedback is just as useful as positive feedback.
    • Atlas
      2027 GMC Sierra: Official Discussion

      By Atlas · Posted

      No tears over the SLE and SLT trim levels disappearing but I kind of loathe the "Elevation" name. It's a truck--skip the elegance.   The slab-dashboard design is decidedly different. Almost has a Hummer flavor to it. "Professional Grade" seems to be leaning very white-collar, tech-driven these days moreso than blue-collar, functional design.   The Silverado would be my choice between the two new trucks. Pleased with the engine lineup in both. The GMC is a little "too much" for a truck, IMO, and the Denali borders on ridiculous - but I do know there are buyers for luxury trucks out there. It's just not my speed.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...