I'll keep this post directed toward those of you with a 2014 and/or 2015 Cummins powered truck preferably with the Aisin auto tranny....however, I suppose any auto will only skew the answer just a fuzz.
My 2015 Ram 3500 SRW CC 4x4 with the Cummins/Aisin power plant is the diesel/HD auto relationship I've waited for since it was leaked out some time ago that this combo would be allowed in the SRW trucks. Not only was a thumbs up given for it, but the motor would also be the high output variant of the 6.7
The day I picked the truck up at the dealer, they made sure both the fuel and DEF tanks were topped off. Now after ~3721 miles of a pretty even city/highway spilt, my DEF gauge shows that it's getting real low. With that said, does that sound normal? My neighbor's 2015 F350 that does 98% over the road driving gets approximately 9-10k miles before he needs to add DEF. Anyone have any idea as to why my truck seems to be thirsty for DEF? Just in case it matters, I'm seeing about 16-17 MPG in town, and 19-20 MPG on the highway....the motor has only 3700 miles on it. Thanks for your help!

 

Looking at my DEF guage (full at new), I would say it was at 3/8ths. I'm just at 3,600 miles.
Back to morning coffee.

 

Have put 1300 miles on mine since I bought it. The def tank was full, and the guage still hasn't moved. It had 12000 miles on it when I got it. Have to see how fast the guage goes down when it starts. Will be pulling the RV trailer next week. From what I've heard, is they use more def when pulling and not alot running around empty. Have to wait and see for mine. Maybe ask your dealer about it? Getting about the same mileage as you.

 

My new 2015 has not moved the DEF gage that is. Still on full would like to know does it work? I have under 2000 miles what do You all think?

 

Our 2015 SRW 3500 CC Cummins Aisin was supposed to be full when we got it. But they used the gage to tell when full. That was a mistake, the gage stays on full for some time and then goes down pretty fast if you are towing, not so fast solo. I let it go to about 3/8 then add a 2.5 gallon box.

Housted

 

After 4,374.8 miles, I put in about one cup shy of 5 gallons. That works out to about 55.377 MPC (miles/cup) or about 866 MPG.
Back to morning coffee. . . ~14 CPD (Cups/Day)

 

I too have just over 4,000 miles on the clock and have used approximately five gallons. Truck came with the DEF tank at 3/4. Just returned from a 3,000 mile trip towing a 32' 5TH wheel all over Oregon, Idaho, Wyoming, Utah and Colorado. It uses more when towing that's for sure. Towed the 5tH wheel like it wasn't even there. Love it. Previous truck was a 08 Ram 2500 LB. Glad I stepped up. (first post by the way).

 

I got 4600 miles out of my DEF tank before the light came on several times saying it was low....the gauge was near empty. I added a 2.5 gallon jug of DEF and it took the gauge to 3/4 full....does that sound about right for just 2.5 gallons? How many total gallons does the tank hold? I will say this about the combo though....as each mile increases, so does my love for this powerplant/tranny combo! The Aisin is a super stout tranny, and the CTD is tried and true for sure. Barring any major problems that surface in the future, this truck will be around for a while as it fills every need that I have. My hopes are that by the time the powertrain warranty expires, there will be plenty of power/delete tuners available that have all the bugs worked out. Everyone that I know with diesels that have the DPF and all the emission crap, seem to have problems/failures once they surpass the 100k mile mark. My neighbor was uninformed enough to actually pay a Chevy dealership to put all new exhaust emission parts onto his Duramax 2500 instead of buying a $185 delete pipe and a tuner to deal with the lights.....needless to say he paid a small fortune for all of it. When he mentioned this to me I told him that he could have picked up power and MPG to delete it all, plus save a bank of $$$ too boot....oh well, he learned his lesson and says he'll go that route with his new Ford 6.7.

 

2500 and 3500 Trucks DEF tank 5.5 gallons, Chassis cab 9 gallons

 

Yep, 5.5 gal. I let it get down to 1/4 or just below then put in 2.5 gal. Takes it up to just over 3/4. This is my third CTD, priors were a 96 and 08. So far, love the 15.

 

I get about 1000 miles per gallon solo +/- and about 700-800 towing 15k 5th wheel depending on hills or flat.

Brian

 

I get about 1300 miles per gallon of DEF. BUT the only thing I've towed is a less than 3000 lb. Bass boat with my '14 2500 68rfe.

A LOT depends on hauling/towing. I know guys with 13+ 3500s who regularly pull 15,000 lbs. plus who carry DEF in the truck for fear of running out on the road.

 

On our last 2 trips I have stopped at truck stops and filled the DEF tank with their pump. It is nice to know that the tank is really full, and BTW the price of DEF from the pump is way less than half the 2.5 gallon boxes. Pumping allows completely full and no spill.

Housted

 

Just shy of 4k miles on the new truck. I've used about 4 gallons of DEF. I drive a healthy mix of towing heavy and driving solo. DEF is cheap and the truck is amazing so I'm a happy camper. 2015 3500 DRW Aisin 3.73 HO