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Duramax Sixth Generation: 2017+ (L5P) Discuss the sixth generation (2017+) of the 6.6L Duramax diesel engine & associated components. Engine related discussion ONLY.


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Old 03-30-2019, 11:22 AM   #61 (permalink)
redwngr
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Originally Posted by Greg S View Post
8.5 hauling a 40' trailer with 2 cars and loads of heavy tools in it. Averaging about 65-70 MPH. Really seemed to suck up the DEF with the big load on it.


Greg
DEF usage is a ratio to fuel usage.

Use more fuel, it will use more def

Should be somewhere close to 1.5 gallons on DEF per 100 gallons of fuel.

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Old 03-31-2019, 05:20 PM   #62 (permalink)
DP218
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This is what my 2018 CCLB has been doing. I have almost 18,000 miles on it since last July and overall hand calculated average is 16.53 mpg over the first 12,500 miles. The trucks on screen mpg shows around the same mpg as well with the best 50 miles at 25.1 mpg and best 400 at 20.7 mpg not towing either time. I run mine around 50 miles one way to work each day going around 65 mph and towing on weekends.

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Old 04-01-2019, 11:08 AM   #63 (permalink)
Greg S
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Quote:
Originally Posted by redwngr View Post
DEF usage is a ratio to fuel usage.

Use more fuel, it will use more def

Should be somewhere close to 1.5 gallons on DEF per 100 gallons of fuel.

Don't mean to doubt this but are you sure that is how its metered? I put in one of those blue DEF boxes and it seemed to be gone in two tankfuls at my towing consumption (8.5 MPG)

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Old 04-09-2019, 09:41 AM   #64 (permalink)
ataboy
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Pulled the boat 400 miles round trip 65mph to 75mph and got 11.7. This is with a 18ft. boat. Scares me about thinking what I will get with the 35ft 5th wheel. I now have 2500 miles on the truck. Just doesn't seem right after pulling with my 2015!
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Old 04-09-2019, 12:00 PM   #65 (permalink)
Mikey52
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Def consumption is a % of fuel used. If you use 100 gallons of fuel, you will use 1-1.5 gallons of def. So when towing, with lower miles per gallon, will yield more def use per mile.
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Old 04-09-2019, 03:33 PM   #66 (permalink)
BanksLB7Duramax
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Originally Posted by Mikey52 View Post
Def consumption is a % of fuel used. If you use 100 gallons of fuel, you will use 1-1.5 gallons of def. So when towing, with lower miles per gallon, will yield more def use per mile.
From what I hear the L5P uses more DEF than that. They use quite a bit more than the LML.
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Old 04-10-2019, 11:16 AM   #67 (permalink)
redwngr
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Originally Posted by BanksLB7Duramax View Post
From what I hear the L5P uses more DEF than that. They use quite a bit more than the LML.
My truck would indicated the 'quite a bit more' is a rumor started by those not correctly measuring consumption. (and those just wanting to hate on DEF)

Probably in part to the continuation of dealers not filling at delivery, complicated by adding to the tank, but not completely filling (so no way to know if it was filled to the same point as last time def was added).

Like the LML, the level 'indicator' isn't accurate enough for determining DEF mileage.



No doubt there will be some that have something wrong with them and will use an unusual amount -- just like happened with some of the LML's.


I guess this is a pointless discussion, unless we are provided with some sort of definition of 'quite a bit more'.
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Old 04-11-2019, 10:46 PM   #68 (permalink)
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350 Miles @ 70 to 75 mph pulling my RV trailer into a 40 mph head wind with rain and snow.
9.4 miles per gallon. (2018 GMC 3500HD)
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Old 04-12-2019, 05:00 PM   #69 (permalink)
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Average DEF usage is around 900 miles/gallon
Average distance between regens is around 830 miles
Average hwy fuel economy is 19.5-20 mpg
Lifetime fuel economy is 18.4 (about 80% hwy and/or rural roads; towing probably <10% of the time)
Best fuel economy (whole tank) is 20.4 mpg
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Old 04-19-2019, 11:18 AM   #70 (permalink)
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25mpg going 55 on flat around with no wind.

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