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Biverson · 08-09-2015, 10:00 AM

We are currently going though 8 gallons of DEF for every 250 gallons of diesel. Is this normal? Seems like a lot.

zman62 · 08-09-2015, 10:23 AM

Quote:

Originally Posted by Biverson

We are currently going though 8 gallons of DEF for every 250 gallons of diesel. Is this normal? Seems like a lot. Sorry, 2015 LA, it won't let me edit the subject.

That sounds like its too much. If you search the entegra forum there is a big discussion on this.

Clayobx · 08-09-2015, 10:29 AM

Way too much!

Selah · 08-09-2015, 10:36 AM

The target usage is 2% or two gallons of DEF per 100 gallons of fuel. You are almost twice that amount. Extensive ideling will cause an increase of DEF but I don't think that much. I would take it to a Cummins shop and have it checked.

loisjop · 08-09-2015, 10:48 AM

Quote:

Originally Posted by Biverson

We are currently going though 8 gallons of DEF for every 250 gallons of diesel. Is this normal? Seems like a lot. Sorry, 2015 LA, it won't let me edit the subject.

Your usage is about 3% the range is 2-4%. Sounds like you're right in the middle. I doubt Cummins will do anything, but if they do let me know because I'm getting a Cornerstone with the isx and would prefer to be at the 2%.

TwoCorners · 08-09-2015, 11:42 AM

We just finished a 7 week trip and used 600.42 gallons of diesel. I started with close to a full DEF tank (4 green bars), added 10 gallons during trip, and arrived home with 4 green bars. Just under 2% DEF usage.

JMonroe · 08-09-2015, 11:59 AM

We were just at the FMCA rally in Madison WI and I attended the Cummins seminar and had a private conversation with the Cummins rep. This interest comes from our considering a new London Aire.

They are now saying to expect usage of between 2 and 4%. As previously pointed out, you seem to be right in the middle of that. Actual use can be affected by how hard you push it, if those 600 ponies are all called to push at once you're going to use more.

DSL417 · 08-09-2015, 12:10 PM

About right.

Hertzberg · 08-09-2015, 12:19 PM

I am doing a bit worse at 3.5% DEF:Fuel with my 2015 London Aire. I recently had the coach in for service and I asked about this. They said that the 600 HP Cummins uses more DEF because the exhaust system is so large.

Smosher · 08-09-2015, 12:43 PM

I have a 2015 London Aire I went to Florida and back to Oklahoma. I can't tell you exactly what it took but it was not much. I also took a trip to Colorado and went over several passes and some good climbs. It used more then twice as much I Thot I had a problem but once I headed home it used very little. My understanding is that def goes in the exhaust after combustion and is injected last to clean the gasses. Which when I was in the mountains it was always claiming and using a lot more diesel. I drive it around 1500 rpm which is right at 63 mph.

Hertzberg · 08-09-2015, 01:24 PM

It does seem like mountain driving uses more DEF. I spent the summer in the West and went over a lot of passes and used a lot of DEF (3.5%). In my recent flatland travels over North Dakota and Minnesota the coach appears to be using less DEF but I haven't measured it yet.

Incidentally, to make calculations easier I measure mpg for both diesel and DEF. In the west I recorded 6.1 mpg for diesel and 170 mpg for DEF. I'll see how this changes now that I am in flatland.

I wish I had the dual-side DEF fill that they offer on the 2016's!

dusty56 · 08-09-2015, 01:35 PM

Biverson your usage is in line with what cummins is stating for the isx15. The bigger the hills and the more you get on it, the more you will use. Usage will be 4 to 6% typically. The smaller diesels will get 2% usage. 250 gallons of diesel and you used 8 gallons of def is actually pretty good.

I like the fact that Newmar put def fillers on the drivers side. Long time needed.