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Old 03-11-2014, 09:18 PM   #1
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Where to buy DEF - cheap.

Having purchased a 2013 Newmar Essex I now require the DEF additive for the Emissions system. My MH which sits on a Spartan Chassis and has the DEF tank on the passenger side, however the Truck Stops (Flying J & Pilot) have the DEF hoses on the driver side pump so in order to fill the DEF tank I have to drive into the fuel island backwards, which displeases most truckers. But the price is only $2.79/gallon.

But there is another option of buying the 2-1/2 gallon DEF boxes. At truck stops they run about $15/2.5g or $6/g. Then I discovered Walmart was about $12/2.5g or $4.80/g. However today I was in a John Deere dealer and they just started selling DEF at $10.14/2.5g or $4.06/g. Additionally the JD DEF has an extra long spout to aid in filling the tank. Very helpful.

Anyway, please post any deals you find out there.


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Old 03-12-2014, 08:13 AM   #2
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Yes, poor implementation in having the DEF tank fill on the passenger side. What I do is carry a few 1 gallon jugs and fill with DEF while at the pump getting diesel. When the DEF levels drop, I dump the containers in the tank and at my next fuel stop, fill them up again so I have a fresh supply.

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Old 03-12-2014, 08:17 AM   #3
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Good short term solution with the jugs, but with proper timing and judicious driving, can you use the 'next' def pump to the right or is it too short to reach ?
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Old 03-12-2014, 08:25 AM   #4
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I have a couple of the 2 1/2 gallon containers from previous purchase. Just fill them at the truck stop, they have the long fill spouts, very useful.
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Old 03-12-2014, 08:28 AM   #5
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Old 03-12-2014, 08:32 AM   #6
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I gotta say this...if you're buying a 2013 Essex...well, does a box of DEF at $12 versus $16 once every couple of months make a difference. If I remember correctly, I've purchased 8-9 boxes in 15 months. 14000 miles. The PITA of moving the coach to fill DEF at the service station, versus $12 versus $16. JMHO, not worth worrying. OTOH, it does grate on me to give the friggin' truck stops an extra $4 a box. So I time my buys to use Walmart. I like the boxes because I think the freshness is more likely.
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Old 03-12-2014, 08:33 AM   #7
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Hadn't thought of filling the DEF in my Silverado at a truck stop. Good idea. I only need 5 gallons. Assume it works just like a gas pump?
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Old 03-12-2014, 09:31 AM   #8
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DEF Pumps at Truck Stops have nozzles that are somewhat similar to fuel nozzles. Here are some known minor issues to be aware of.

Some truck stops require purchasing diesel before allowing purchase of DEF. The truck stop diesel nozzle requires some practice or skill to fill an automotive tank without overflow.

The DEF nozzle is a snug fit in the fill neck on your truck. Some nozzles have magnetic interlocks to make putting DEF in a diesel neck impossible. Your truck should be equipped to be compatible with magnetic interlocked nozzles. Again some skill and practice is required before filling your truck's 5.5 gallon tank without some overflow.

Filling containers with DEF at the pump is a great way to get "reserve" DEF for later use on your vehicle. On nozzles with the magnetic interlock, a special collar is needed to allow dispensing DEF in a container. Containers for reserve DEF should be sealed, clean, rugged, have leakproof caps, and must be made of DEF compatible material (like polyethylene) to avoid contaminating the DEF which could result in damage to your truck's SCR system (expensive). Don't use your reserve DEF container for anything but DEF to avoid contamination. An occasional rinse of the container with distilled water (NOT tap water) will help avoid sediment getting in your DEF tank which can clog the DEF system filter which is somewhat expensive to replace. The DEF doser nozzle in your truck's exhaust has a very small opening, requiring very fine filtration of about 1-5 microns.

There has been some debate about the quality of bulk DEF at truck stops vs. jugs. I've tested a lot of DEF for urea concentration, and have never found a reading out of specification range at a truck stop. Your truck has instrumentation that can detect diluted DEF, and will require you to take care of the issue by "intervening" in the operation of your vehicle. I ALWAYS sample DEF for urea concentration prior to refilling my tank.

One thing to watch on pre-packaged DEF is the expiration date printed on the jug. Shelf life is 2 years in a controlled environment under 72F, less in warm conditions. DEF decomposes into ammonia at any temperature above 50F or so. After 2 years at 72F, the DEF has at least .2% ammonia dissolved in it, and ammonia vapor in the air space in the jug. Still works fine in your SCR system, but it will be used at a slightly higher dosing rate and there are issues with specification and API compliance of old DEF. The expiration date on jugs is coded. I'll do a post someday with the magic decoding ring for common Jug expiration date codes...I recently found a 1 gallon jug at the local O'Reilly that was over 2 years old and had urea crystals all over from venting at the cap.

Warmer temperatures result in faster decomposition and higher levels of ammonia in the DEF and higher pressure ammonia vapor in the airspace. Unsealed jugs continuously vent ammonia, especially in warm temperatures. We recommend storing your reserve DEF in a vented compartment on your vehicle.
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Old 03-12-2014, 10:05 AM   #9
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Five starDEF. So when the DEF is diluted the injection system know this and inject more??

I've heard that one idea was that water could be used as the urea is aprox 70 % water??

I don't have a clue. I see you say that the system knows when diluted. Does it shut you down or how does that work.

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Old 03-12-2014, 10:32 AM   #10
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We have a filling station here that sells the 2 1/2 jugs for 9.99. I try to buy it from them.

I90 exit 46 in South Dakota, Elk Creek exit. Also way cheaper for diesel then the Rapid City truck stops.
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Old 03-12-2014, 10:49 AM   #11
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Old 03-12-2014, 11:32 AM   #12
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Our Sam's Club (North Texas) has the 2.5 gallon boxes for just under $11.
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Old 03-12-2014, 02:15 PM   #13
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Those are excellent prices for 2.5 gallon jugs!

Answers to Challenger RN:

1. So when the DEF is diluted the injection system know this and inject more??

Answer: Yes. DEF dosing is under closed loop control. There are NOx sensors AFTER the SCR unit. If NOx is detected above the control point, additional DEF is dosed. If DEF is diluted, it is less effective at reducing NOx. The system continues to increase DEF dosage until NOx is at the required control point. If the system is unable to reduce NOx to the required level, your vehicle will have an intervention (speed reduction, and eventually shut down to idle until the problem is fixed). This intervention approach is Federal Law enacted by EPA2010 protocols.

2. I've heard that one idea was that water could be used as the urea is aprox 70 % water??

Answer: Not recommended, but it's up to you. Indeed, DEF is 67.5% pure water by weight. VERY pure water. The other 32.5% is pure Urea. VERY pure Urea. The urea in DEF is turned into ammonia (NH3) by the heat in your exhaust. The ammonia is what works in your SCR unit to eliminate NOx. No Urea, No ammonia, NOx uncontrolled, vehicle will have an intervention. Can be avoided with major modifications to your vehicle and reprogramming your engine ECU, but not recommended. The EPA has begun shutting down "Tuner" and "Delete" manufacturers and this will likely continue.

3. I don't have a clue. I see you say that the system knows when diluted. Does it shut you down or how does that work.

Answer: See number 1. Check you owner's manual or consult the manufacturer. Interventions vary by manufacturer, but all must meet EPA2010 which requires the SCR system be operational and reducing NOx to the required levels.

Good questions!

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Old 03-12-2014, 02:22 PM   #14
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Thanks. Very good explanation


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