What is DEF?

Discussion in 'PAM' started by Scoundrel, Oct 8, 2011.

  1. Dna Mach

    Dna Mach Road Train Member

    Aug 8, 2008
    You also get around 300 miles per gallon of DEF fluid. Most trucks have 20 gallon tanks so it's nothing you have to worry about to often.
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  3. Rollin2003

    Rollin2003 Light Load Member

    May 9, 2011
    They should have given you the video to watch..
    But remember this:
    DON'T put DEF in your fuel tank or put fuel in your DEF tank.
    When you are down to 2 green lights if will take 2 of those 2 1/2 galllon boxes.
    If you see DEF at the pump you can use your Com Card to fill DEF only.
    If the DEF lights get to the last light and it turns yellow, the max speed your truck will run is 55 mph.
    If you still wait after that and it turns red, the max speed is 5 mph.
    If the DEF spills on your metal it will corrode it, so wipe up any spills.
    Other than all that just keep it above 1 light and filled.
  4. SMBdriver

    SMBdriver Light Load Member

    Nov 28, 2010
    DEF is deionized water and high purity urea in specific proportions. You can get it at most auto parts stores for about 13 bucks for 2 1/2 gallons, and (I hear) supposedly a lot cheaper at the bulk pumps at some truck stops.

    I personally have only seen 1 bulk pump and that was in Russellville, Arkansas on the closest fuel lane to the door of the truck stop. (Think it was the Flying J) The rumor is that they're putting more of them in at more locations.

    On my little Dodge truck, if I let it run out, I get a 500 mile warning and if I don't refill it before that ticks down to zero, the truck is not supposed to re-start. Haven't tested that.
  5. maxwelltie

    maxwelltie Medium Load Member

    Mar 13, 2010
    Brookings, OR
    Bulk DEF is available at many Pilot and J locations. And the number offering it in bulk is increasing quickly.
    DEF sells for about 2.69 per gallon at the pump. About a third the cost of buying in the box.
    If you run in the areas that have the bulk, don't worry. But if you get into the Northeast a lot or other areas without bulk, keep and extra carton with you and refill it if necessary when you're at the bulk dispensers.
    Now if you're a company driver and it doesn't count against you, do as you please. For those of us that buy all our own fuel and liquids, bulk is MUCH cheaper.
  6. bigjoel

    bigjoel Road Train Member

    Jan 20, 2011
    Houston, Tx
    What would happen if you ran the DEF tank dry?

    Would it shut down, or damage anything?

    Just wondering.
  7. Dna Mach

    Dna Mach Road Train Member

    Aug 8, 2008
    The truck will offer ample warning and then derate allowing you to get to the shoulder of the highway. They will not run without DEF fluid.

    When my Peterbilt DEF guage is on empty and my warning light has moved from solid red too flashing red, I still have 5 gallons left. That will get me about 1500 miles before it runs dry. You pretty much have to intentionally run it dry. At that point I would imagine it would suck accumulated gunk from the bottom and cause problems since the DEF system is very prone to malfunction with very little contamination.
    bigjoel Thanks this.
  8. Prairie Boy

    Prairie Boy Road Train Member

    Nov 18, 2010
    Edmonton, AB
    aka DEFACATOR. It uses liquid 34 - 0 - 0 fertilizer and 2/3 water mix.
  9. GSWx

    GSWx <strong>Doc In The Box</strong>

    Aug 13, 2011
    Coastal Alabama.
    I don't know about the big trucks, however in my 2011 HD 2500 pick-up truck, the manual says that once the DEF runs out, engine speed will be limited to 45 mph until replenished. The manual was right.
  10. Karen_A_Smith

    Karen_A_Smith Bobtail Member

    Jun 3, 2011
    Lincolnshire, UK
  11. Drivin_Dave

    Drivin_Dave Bobtail Member

    Oct 1, 2011
    Lemme get back to ya on that .... naw, I don't think so, my Trans Shop Mgr would be "pissed" at me!

    Dryver, you gotta quit watchin' Mythbusters and IRT while you're dryvin'!:biggrin_25522:
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