Def usage?

blamkin86 · March 15, 2020

Hi all. 2020 3500 gmc AT4.

I’ve had it three weeks and love it.

Quick question: is anyone noticing high DEF usage? We went on a 2k mile trip last week and used 75% of the tank at 1500 miles and had to top off. Seems really high to me.

Thanks all.

Tomato · March 15, 2020

It does seem higher than my 2015 Duramax. I have about 1,200 miles and added 2.5 gallons - got to 1 mark less than full. Old truck would go about 4,000 miles and take 2.5 gallons to fill it up.

dab5577 · March 15, 2020

I’ve also noticed it seems to have higher consumption rate than my 2015. I have around 6500 miles and it’s almost ready to be filled again for the third time.

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jaybauman · March 15, 2020

With my 2015 2500HD Duramax, I added DEF about as frequently as I changed the oil (once per 5000 miles). I had to add DEF on my 2020 3500HD for the first time at 3600 miles (down to 1 bar on the DEF gauge). I'm somewhat disappointed about the increased DEF usage....

AT4 HD Ron · March 18, 2020

I thought the same thing at first, but the usage seems to have normalized after like 6K miles. I don't think the gauge is very accurate and mine definitely was not full on delivery. After getting it topped off, usage and miles per fill up seem very similar to my 2014.

Edited March 18, 2020 by AT4 HD Ron

CRApex · March 18, 2020

I have 19,500 on my 2020 and it certainly seems like it uses more DEF than my 2017.

Edited March 18, 2020 by CRApex

migrabill · March 18, 2020

Mine (2020) was only half full at delivery. I tried to add more and the truck would not take any more. After about 2000 miles I was 2 blocks away from empty. I added DEF till it wouldn't take anymore. Gage is still only reading half full. Any clue?

CRApex · March 19, 2020

22 hours ago, migrabill said:

Mine (2020) was only half full at delivery. I tried to add more and the truck would not take any more. After about 2000 miles I was 2 blocks away from empty. I added DEF till it wouldn't take anymore. Gage is still only reading half full. Any clue?

I've noticed mine won't show full right away, seems to take a while. Not sure why.

withee1319 · March 19, 2020

I topped off completely when I brought it home from the dealer at 70 miles. I just noticed the other day it says 1/2 tank of Def at 2900 miles.

Wlb88 · March 21, 2020

I have 6,200 miles on my 2020 and it just notified me that I have 700 miles until empty. This will be the 2nd full tank of DEF it's used.

Leon Baehre · April 9, 2020

We just returned from spring break in Texas. We are from Michigan and we put on 3600 miles pulling a 8000 travel trailer with 2020 LTZ Duramax. This is our first experience pulling a TT with a diesel, what a great experience. We have 48000 miles on the TT, most of them with a 2014 GMC Sierra SLT with 6.2 liter and max tow. We had 1200 miles on the truck when we left and DEF was one bar from full. We had to Def 4 times. Usage was erratic, Sometimes we got well over a 1000 miles on the DEF and then needed 4 gal, other times less that 500 miles and had to add 4 gal. Interesting using truck stops to pump DEF. Another new experience, Need to come up with a better way to deal with them. Loves will not take a personal credit card at the pump, must go inside and authorize $100, then go back inside to get the receipt. Not fun with Covid19. Diesel is much cheaper at non ruck stops, but no DEF at the pump. I am ordering a DEF container so I will have 2.5 gal in reserve in the back of the truck.

Thomas E · May 27, 2020

My 2020 is using almost three times the amount of DEF that my 2017 used.

I ask the service department about it. They said if the check engine light is not on, there is a problem. I said "except that the cost of DEF usage has tripled now".

MTU Alum · May 27, 2020

The emissions requirements have tightened since 2017 so will have to use more def to be compliant.

#iworkforGM

doverarjim · May 27, 2020

My 19 model has been using more DEF than my '11 truck did, in 165,000 miles on the '11 truck DEF cost was $0.00244 per mile. The '19 truck at 49,850 the cost for DEF has been $0.00511 per mile. I have noticed the cost of bulk DEF has gone up the last few years, but I have only used bulk since I first saw it at the local Flying J in 2012!!! with the larger tank in the '19 it is going less miles on average than the '11 truck got about 6,500 miles to tank and the '19 is going about 5,000. :jester:

Steve.S · November 17, 2020

I have the 2020- GMC 2500HD Denali Diesel and at 8,000 miles I have used a total of about 17 gal def fluid. Gauge I know is erratic, but think it may be related to info cluster problems I am having. Anyway at one point I stopped and fueled and topped off def. at about 100 miles warning came on saying DEF low. Over the next 28 miles (next fuel exit) I watched the indicator drop to the last mark. It took 6 gal to fill. Wow I thought it won’t make it home t this rate! Got in and drove 490 miles to next fuel stop and DEF only showed down one bar?/// I thought it was a fluke, so continued . When I stopped at a dealer I was told they don’t have a way of saying how far you can go on a DEF tank and it could vary, no check engine light, and was told they would not find anything unless code shown. So advised me to go on and watch it, or leave it and they would work it in some time that day or next morning! Ok is it me? Is it the truck? Or is it dealers that

don’t know what to look for? So in 8,000 miles it has happened three times, I have gone through at least 17 gal or more of DEF, (I still have the empty bottles to show for it) I have only seen one “Regen cycle” and I am setting at dealer now while they look to see if there is problem... Which I am now told they see nothing wrong with truck, no codes, no problems found? Everything normal... Now I didn’t answer any questions, and I didn’t give any ideas,,, but I feel better about sharing and writing my frustration! Haha maybe someone will have an answer, but I am buying stock in DEF if I can, I might get my money back on used fluid..

adding this 11/19/2020. Dealership cannot explain usage, although they believe is high, said “there is no sender in the DEF tank, no communications method to say what level of DEF fluid is actually in tank” so how does the display know? And how can it be reliable? Am I dumping it on the road? Where is it going and why? it is hard to believe it does not have a level sensor!

Edited November 19, 2020 by Steve.S