Forum Discussion

catkins's avatar
catkins
Explorer II
Mar 25, 2017

DEF Usage 2014 Tiffin Red with Cummins Diesel

Just got info for an RV tour to the Maritime Provinces in Canada. They advise that DEF at the pump is not readily available in some areas. I always just fill when I get down to a half a tank so am not sure what my consumption will likely be.

Any of you good record keepers able to give me a ballpark rate of use?
I will start with a full tank and take extra DEF with me, Since running out is NOT an option, want to be sure I take enough. Will of course top off just before entry into Canada.................

Appreciate any wisdom out there. Long time RVer but first diesel and still learning.
Class A
  • nevadanick's avatar
    nevadanick
    Explorer
    Mar 26, 2017
    I had a 2104 red and was always towing heavy and if i remember right it was about 500 mi to the gal. You can buy jugs of it in Canada if you need more. A full tank and a couple jugs should get you anywhere you want to go. I now have a Phaeton with 8.9 ISL and on trip to Ak used the 2 i carried and bought 2 in Canada along the way.
  • tomman58's avatar
    tomman58
    Explorer
    Mar 26, 2017
    My GMC 2015 tells me when I have to refill. It also tells me when I have 1000 miles to go before refill. I don't think you can drive 1000 miles in the US without a number of truck stops that have it.
    This stuff has a shelf life and get old in 2 years so why bother paying more then at the pump?
  • crasster's avatar
    crasster
    Explorer II
    Mar 26, 2017
    Two Jayhawks wrote:
    I have a 8.9L and I keep records. I use about one gallon for 280 miles.
    I suspect yours would use less. How large is your DEF tank?


    Very smart to keep records of this. It shocks me how many don't. It's simple enough to calculate w/fuel fills.
  • Mr_Mark1's avatar
    Mr_Mark1
    Explorer
    Mar 26, 2017
    Our 500 hp Volvo uses (est.) about one tank of DEF (16 gallons) to two tanks of diesel (460 gallons).

    Basically, I fill the diesel at 1/2 a tank so I fill the DEF every other tank full when it reaches 1/2 a tank.

    Safe travels,
    MM.
  • haddy1's avatar
    haddy1
    Explorer
    Mar 25, 2017
    50 to 1 is a good rule of thumb. ie: One gallon of DEF for every 50 gallons of diesel burned.

    If you are really concerned about running short, pick up a couple of containers at Walmart (about $8 for 2 1/2 gallons).
  • Mile_High's avatar
    Mile_High
    Explorer
    Mar 25, 2017
    After driving our F350 that got over 5,000 miles on a tank of DEF, I was shocked how much our Cummins 8.9 used, but of course the Cummins has a lot larger DEF than the F350 had.

    3,200 miles we added 10 gallons.
  • catkins's avatar
    catkins
    Explorer II
    Mar 25, 2017
    340 Cummins, average 7.5-9.5 mpg diesel. Believe we have a 13 gallon DEF tank, currently in storage but retrieving for service this week.

    Will be checking usage as we head east from Seattle but hoping for a ballpark estimate with real time usage with similar engine/rv. Thanks.
  • Two_Jayhawks's avatar
    Two_Jayhawks
    Explorer
    Mar 25, 2017
    I have a 8.9L and I keep records. I use about one gallon for 280 miles.
    I suspect yours would use less. How large is your DEF tank?
  • lryrob9301's avatar
    lryrob9301
    Explorer
    Mar 25, 2017
    It varies by engine size and fuel mileage. My 8.3 L 380 HP Cummins uses about 2 gallons of DEF to every 100 gallons of diesel fuel.

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