DEF usage

[Mark S]

I know I’ve read that DEF use should be about 50 to 1 to diesel. It seems like I’ve been using more DEF lately so I checked the last few tanks and I’m getting about 30-35 gallons of diesel to one gallon of DEF. This is under similar driving while towing and not.

Has anyone kept track of their DEF usage?

[SloPoke]

Mark,
The most I have payed attention to the DEF useage is...

One light - get some with the next fuel stop
Two light - keep going
Three light - good shape
Four light - well.... that was an expensive stop

[Grumpy]

It can be as high as 3% so what your seeing is not unusual.

[Robbbyr]

Mine has never been that high, are you towing a heavy load in mountainous country Mark?

[Mark S]

Originally Posted by Robbbyr

Mine has never been that high, are you towing a heavy load in mountainous country Mark?

No Rob, towing my Jeep in Florida.

[Les7h]

I have always got around 330 mpg - about the same towing as not - Freightliner says that my engine is working harder than the 8.9 and so it uses more DEF than the 8.9


Les

[Mark S]

Makes sense. You are right about where I am. So I guess 2.5-3 % is normal.

[GHen]

I use 5x the def when towing my 5th wheel in the mountains. My gauge shows miles left when it gets below 20%. It’s normally pretty accurate. Last summer when towing it showed 600 miles until empty so we headed to our next spot, after only 100 miles I had 10 miles left to get it filled. I was sweating for a awhile there until I found a convince store. I now always carry an extra when towing.

2017 Chevy Duramax 2500.

[Crossingover]

We're averaging 392.8 miles/DEF gallon.

[Mark S]

Originally Posted by Crossingover

We're averaging 392.8 miles/DEF gallon.

That’s pretty good. What kind of diesel mpg are you getting?

[Crossingover]

Originally Posted by Mark S

That’s pretty good. What kind of diesel mpg are you getting?

Long term average is 8.8; we roll gently up to 62 mph most all the time.

[McGintys924]

Originally Posted by SloPoke

Mark,
The most I have payed attention to the DEF useage is...

One light - get some with the next fuel stop
Two light - keep going
Three light - good shape
Four light - well.... that was an expensive stop

That was hilarious!! Admittedly I have not measured my usage but my recent trip from Galesburg, IL to Jayco and return has me at a yellow light. That is about 680 miles plus whenever Jayco did when they had it. That being said I will see how much it takes when I fill it up. Next trip in a month and will try to include a more exact measurement.

[Jimmyd]

Mark S,
On a previous 2015 Class A with 450 Cummins we were averaging 400 miles per gallon of DEF. As noted by Crossingover we also rolled at 62 mph most time.
Hope this helps. Jimmyd

[Lake Huron]

I keep pretty detailed records on my trucks. My uncle has a 2011 and a while back he said he can go between 6000 and 6500 miles before he has to fill his DEF tank with 5 gallons of DEF fluid.
Here's my findings;
2011 3500 crew dually 4x4
51960 miles on the odometer and it was filled with DEF 12/9/2013
Late 9/2014 it traveled 6463 miles, used 499.2 gallons of diesel fuel and ran for 487 hours during this period and took on 5 gallons of DEF. Doing the math my mix rate is 99.84:1 The truck didnt get driven much between 12/2013 and 4/2014. It then became my daily driver and towed our 34' Montana Mountaineer 5th wheel when we went on weekend trips.
So that lined up with what my uncle was saying about his.

2015 3500 crew dually 4x4
8564 miles on the odometer and was filled with DEF 7/31/2017
Mid 8/18 it traveled 3724 miles, used 337.4 gal of diesel and ran for 110 hours.during this period and took on 5 gallons of DEF. Doing the math the mix rate is 67.48:1.The truck wasnt driven when it was put away for the winter in 11/2017 and came back out in late 3/2018. Drive patterns of this consist of once in a while it gets driven to work, church on sunday and pulls our 44' Northpoint.

So, either way both of these truck are mixing DEF to diesel WAY better than the 50:1 ratio. One much better than the other, but mileage are not close to being the same on them and drive patterns are different. Towing is considerably different between them due to the Northpoint being MUCH heavier, longer and taller than the Montana.