3.0 Duramax DEF consumption

ullose272 · May 11, 2020

I have 1400 miles on mine, 3 bars down on DEF. Ive towed about 300 miles of that, a 3500 lb boat. Average 17mpg towing.

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topgear1224 · May 11, 2020

Remember DEF usage is supposed to be tied to fuel usage.

The ratio would be DPF used per gallon used.

Anyone have any information from GM as far as what would be considered excessive? I know Cummins has a max usage guideline.

My gauge was correct. I just drove it till it said it was gonna limit me to 65. it took all 5 gallons I put in. The gauge needs to be a radial gauge not a bar graph.

Dealer told me to expect to fill up 5.5 gallons every 2 tanks in winter....... So 1 gallon of DEF per 8.3 gallons of diesel........

5 gallons of DEF costs between $20-$30 up here in Fairbanks. That's the bulk price too.

Dealer also confirmed they did infact full it full when they put it on the lot. So I used 5.5 gallons over 2650 miles (107.42 gallons).

EDIT: Added number of gallons used.

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topgear1224 · May 11, 2020

I purchased my 3.0 duramax in February. Filled tank right away. At 2500 miles (not towing averaging 24+ MPG) i was 2 bars below full. I decide to take a trip TOWING a 4500lb enclosed trailer (total weight). After 200 miles at 12.7 MPG alert came on saying 278 miles def remaining and gauge was now 1 bar above 1/2 tank. in 125 miles the low light came on and in another 50 miles alert came on saying empty and could drive x miles before power affected. I had to drive 20 miles to get def. Filled tank & it took about 4.2 gallons. as soon as got going alert came on saying less than 1000 miles remaining. After 500 miles alert said 258 miles remaining and gauge was 1 bar above 1/2 tank. in less than 120 miles empty tank alert came on again. I had purchased def and had with me. Took 2.5 gallons Plus not quite the rest of 1st box (about .8 gallon, so basically 3.2 gallons WHEN TANK SAID EMPTY. When started up alert came on and said 750 miles remaining right after fill. Drive about 650 miles and 1st low light came on. Stopped and installed 2.5 gallons I had. It probably could have taken more but gauge showed full. Drove another 300 miles home and when restart alert says 280 miles remaining. Basically I used about 11 gallons to go 2,225 miles averaging 12.7 round trip (10.8 worst and 15 best per tank of fuel). Every time gauge drop from 1 bar above half to empty in around 120 miles. Have appointment at dealer on Monday morning to atleast get gauge checked out. Was really hoping would use less def, But really have issue with gauge

Truck has plenty of power for my size load. On flat Nebraska road RPM ran 1,750 to 2500 with occasional 3.2 running 77 MPH. In mountains had worst mileage at 10.8 but still had enough power to hold 65 up Loveland pass (my old 5.3 would not hold 55 at top). Best mileage on 2 lane roads at 65 MPH

You were beating the absolute snot outta it to get the MPG THAT low (not that it's a bad thing). Your oil temps have be over 350°.... And from the CAN data I've seen, I bet your intercooler was out to lunch. I see oil temps of 280+ unloaded. Did you notice it derating on you?

On the 3.0 3/4 throttle is actually full throttle. Towing at 77 mph seams awfully high. I haven't seen tires rated over 75 for trailers.

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BJ Niceguy · May 11, 2020

actually it pulled great and never felt it was working near as hard as my old 5.3. 10-speed shifted smooth. Temp gauge never came up. Speed limits in midwest are 80 in a lot of places on freeway and truck oil life never spiked at all (went down consistant with 1st 2500 miles, not related to fuel mileage. Basically happy except def gauge is weird. Def consumption seems high but will live with it if they get gauge where know where I am at (Not going down very little, then jumping to empty). Again don't feel I was working truck hard and has not used 1/2 quart oil in 4700 miles

redwngr · May 11, 2020

6 minutes ago, topgear1224 said:

Remember DEF usage is supposed to be tied to fuel usage.

The ratio would be DPF used per gallon used.

Anyone have any information from GM as far as what would be considered excessive? I know Cummins has a max usage guideline.

My gauge was correct. I just drove it till it said it was gonna limit me to 65. it took all 5 gallons I put in. The gauge needs to be a radial gauge not a bar graph.

Dealer told me to expect to fill up 5.5 gallons every 2 tanks in winter....... So 1 gallon of DEF per 8.3 gallons of diesel........

5 gallons of DEF costs between $20-$30 up here in Fairbanks. That's the bulk price too.

Dealer also confirmed they did infact full it full when they put it on the lot. So I used 5.5 gallons over 2650 miles.

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When DEF use began with the 6.6L LML Duramax, GM published a document indicating that DEF consumption should be (IIRC) about 1.75% of fuel -- so a little less than 2 gal def per 100 gal fuel.

I haven't seen or heard of a similar document for the 3.0L.

I'm running 1100-1200 miles per gallon of def with this 6.6L (rarely tow with it)

What's fuel cost at the locations charging $4/gal for DEF?.

topgear1224 · May 11, 2020

actually it pulled great and never felt it was working near as hard as my old 5.3. 10-speed shifted smooth. Temp gauge never came up. Speed limits in midwest are 80 in a lot of places on freeway and truck oil life never spiked at all (went down consistant with 1st 2500 miles, not related to fuel mileage. Basically happy except def gauge is weird. Def consumption seems high but will live with it if they get gauge where know where I am at (Not going down very little, then jumping to empty). Again don't feel I was working truck hard and has not used 1/2 quart oil in 4700 miles

Yeah GM doesn't include an oil temp gauge on the dash and seeing the numbers that I've seen in the OBD2 data I know exactly why. Let's just hope dexos D is a full synthetic......

I do want to point out one unique feature that this engine has that it shares with, the L5P is that it actually uses centrifical Force to separate oil vapor in the PCV system this means that the engine should never ingest any of its own oil. It's like a catch an that automatically drains to the oil pan.

Does your gauge cycle between 200-220 too?

EDIT Added more content.

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topgear1224 · May 11, 2020

When DEF use began with the 6.6L LML Duramax, GM published a document indicating that DEF consumption should be (IIRC) about 1.75% of fuel -- so a little less than 2 gal def per 100 gal fuel.
I haven't seen or heard of a similar document for the 3.0L.

I'm running 1100-1200 miles per gallon of def with this 6.6L (rarely tow with it)

What's fuel cost at the locations charging $4/gal for DEF?.

They don't sell it at the pump in Alaska. the closest you're going to get is buying it from Walmart even the big fleets have to buy it in "bulk" from Walmart.

This also means that randomly they will completely sell out of all of their DEF. And well at that point you have to go to the dealer and pay 27.99 per 2.5 gallon (haven't checked if Ford or ram is cheaper) they only get in once a month.

when I bought some this week in the most recent manufacture I could find was February.

So I used 5.5 gallons of DEF and during that time I used exactly 107 gallons of fuel....... dealer says to expect it to fall to 1 gallon of DEF to 8.7272 gallon during the winter. (Which is basically October to May)

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BJ Niceguy · May 11, 2020

No, mine seems to hold 210 degrees consistent. Got truck back from dealer with usual "nothing wrong with it". I had left it down to 1 bar above half and they did not even add any def to see how much it would take to fill from that point. They gave me a GM document dated 4/7/2020 stating that all the new duamax engines Colorado to 6500) may use more def than you may think. It had 1 sentence stating that the gauge does not work like a float gauge for fuel. Nothing more on how it works or why not just a normal gauge. The computer has to know exactly how much is left or it could not tell you how many miles you have left based on some fuel mileage at start up, so why can't the gauge be accurate on remaining volume?

topgear1224 · May 12, 2020

No, mine seems to hold 210 degrees consistent. Got truck back from dealer with usual "nothing wrong with it". I had left it down to 1 bar above half and they did not even add any def to see how much it would take to fill from that point. They gave me a GM document dated 4/7/2020 stating that all the new duamax engines Colorado to 6500) may use more def than you may think. It had 1 sentence stating that the gauge does not work like a float gauge for fuel. Nothing more on how it works or why not just a normal gauge. The computer has to know exactly how much is left or it could not tell you how many miles you have left based on some fuel mileage at start up, so why can't the gauge be accurate on remaining volume?

Ya in the OBD2 freeze frame from an recent CEL. It showed how full DEF is in gallons.

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topgear1224 · May 12, 2020

No, mine seems to hold 210 degrees consistent. Got truck back from dealer with usual "nothing wrong with it". I had left it down to 1 bar above half and they did not even add any def to see how much it would take to fill from that point. They gave me a GM document dated 4/7/2020 stating that all the new duamax engines Colorado to 6500) may use more def than you may think. It had 1 sentence stating that the gauge does not work like a float gauge for fuel. Nothing more on how it works or why not just a normal gauge. The computer has to know exactly how much is left or it could not tell you how many miles you have left based on some fuel mileage at start up, so why can't the gauge be accurate on remaining volume?

When I eventually get my truck back from the dealer I'll find out the PID (OBD2 address) for DEF level in gallons.

You can grab one of those cheap BT adapters and view the data. I like MXLink only because the app is actually pretty good for being "free" (only works with their adapters.

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BJ Niceguy · May 12, 2020

so if I purchased a MX+ like below (I have I-phone so most won't work) I could view actual volume in def tank plus oil temp etc? Don't really want a bunch of extra stuff, but a phone app seems reasonable. I buy this rather than even call GM and ****** since I know they won't do anything about gauge except tell me I don't understand LOL

( https://www.amazon.com/OBDLink-Bluetooth-Professional-Grade-Diagnostic-Performance/dp/B07JFRFJG6?ref_=ast_sto_dp )

topgear1224 · May 12, 2020

so if I purchased a MX+ like below (I have I-phone so most won't work) I could view actual volume in def tank plus oil temp etc? Don't really want a bunch of extra stuff, but a phone app seems reasonable. I buy this rather than even call GM and ****** since I know they won't do anything about gauge except tell me I don't understand LOL

( https://www.amazon.com/OBDLink-Bluetooth-Professional-Grade-Diagnostic-Performance/dp/B07JFRFJG6?ref_=ast_sto_dp )

Ouch I paid $60 for the same one. Ok so oil temp yes I am 100% sure.

DEF, so I know I saw gallons remaining in the freeze frame (freeze frame is like a snapshot of various sensors at the moment a check engine light was caused) that was a few hours before I dropped my truck off. I haven't tried to add it to my dashboards in the app.

I have attached the dashboard layouts I use. You can do so much more.

I have no idea what coolant 2 is as far as the sensor location. I believe it to be the intercooler but I see temps over 300 and technically that shouldn't be possible with only a 5 psi cap.....

Basically I won't know if you can easily view DEF remaining, until I get my truck back. I know it was in the freeze frame so it should be able to be added.

I will bring up one thing these trucks are so new you really need to know what sensor the reading is coming from and where it's located. for instance the oil temp sensor could be before the oil cooler, I don't think it is, but it's possible.

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topgear1224 · May 12, 2020

so if I purchased a MX+ like below (I have I-phone so most won't work) I could view actual volume in def tank plus oil temp etc? Don't really want a bunch of extra stuff, but a phone app seems reasonable. I buy this rather than even call GM and ****** since I know they won't do anything about gauge except tell me I don't understand LOL

( https://www.amazon.com/OBDLink-Bluetooth-Professional-Grade-Diagnostic-Performance/dp/B07JFRFJG6?ref_=ast_sto_dp )

Just got my truck back, codes cleared so no freeze frame to reference. It can show you a % of full down to 2 decimal points. So mine shows 85.89% full. (4.72 gallons remaining)

If you find a PID code for an gallon level (similar to how I got the trans gear to show on mine) you can add it.

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BJ Niceguy · May 12, 2020

yes if I had android phone only $69 I think. I ordered and will get in few days. Will be nice to see gear too besides other stuff. No tow trip planned soon, so will have to play with it before need / want. Won't be first money wasted if don't work on def. Built a rack in trailer to hold 2 boxes of Def for trips. Will buy fresh just before leave so no age issues.