Hello all. This thread brings up a lot of great subjects. We've done a LOT of research and testing of DEF since we bought our 2013 F350 for carrying our Arctic Fox, and we ended up starting a company to try and solve some of the issues we found, especially storage. DEF and Clean Diesels are one of my retirement hobbies. The VERY long technical story can be found on our website, but I'll try and provide brief answers to some of the questions raised here (but it is still a long reply
1. Clean Diesel (2010-on) Light Truck Emission Control systems use DEF to reduce NOx in a Selective Catalytic Reduction (SCR) converter. This system allows MUCH less EGR contribution, thus much better performance and economy.
2. DEF is dosed 2%-5% depending on conditions AND quality of the DEF. It is a closed loop control system that adds DEF based on real time measurements of NOx in the exhaust. Thermally degraded (old) or diluted DEF contains less urea, so is dosed higher. DEF degrades in the vehicle tank due to temperature exposure, and is dosed at a higher rate.
3. The Diesel Particulate Filter (DPF) is completely separate from the DEF/SCR system and is UPSTREAM of the SCR. However, recent testing by engine manufacturers of higher doses of DEF in the SCR system (up to 6% at high soot conditions) could eliminate DPF, dramatically increasing performance and mileage in the near future. Expect this to be on the 2018-on light diesel trucks. Expect a reflash of your truck or RV's ECU that increases your DEF dosing at about the same time.
4. DEF purity is very important. The SCR catalysts that make the system work are VERY sensitive to metallic, dissolved solids, and other impurities. Think about how hard water clogs a steam iron or humidifier. Same thing happens with impurities in DEF and the doser/injector/catalyst. Metals (like copper, iron, aluminum, etc) in DEF "plate" the catalyst and destroy it. Just like lead was taken out of gasoline to allow catalytic convertors to work, DEF can't have any dissolved metals in it. Using a steel tank for reserve would be unwise. A non-working SCR system will quickly be detected by the NOx sensors and unpleasant consequences can occur. Use caution with non-DEF containers (don't use any container that is not polyethylene or poly propylene) and rinse it carefully with distilled water before use. We've made and used our own DEF for over 10000 miles on our truck using automotive grade urea and distilled water. We've passed the required ISO/API testing (at a cost of $675) and have run hundreds of tests of urea % on various sources of DEF. I can teach anyone that wants to know how to make the purest DEF you can get. Questions? Use PM to discuss at length.
5. We're developing an alternative to the $30 magnetic collar. I'll let you know how it turns out.
6. We attended a Diesel Emissions and DEF Conference last year, and met all the industry players and engine makers. DEF is BIG business: 367 million gallons are expected to be sold in 2014, most to heavy trucks. (that's over $1B sales just in DEF). Effective this year all off road equipment (farming, mining) are required to use SCR/DEF. Rail already has it. Marine starts in 2017 including recreational boats. The typical SCR system in a light truck or RV adds about $1500 to the price, and about $4000 to replace.
7. The most common maintenance item on a DEF system (now that most of the bugs have been worked out by the manufacturers) is replacement of the filter (about a $200 repair). The life of this filter is directly related to the quality of the DEF you use.
8. We don't carry reserve DEF on our truck for lots of good reasons (ammonia triggers my asthma and DEF jugs can vent ammonia when it is stored over 90F). We carry pelletized automotive grade urea prepackaged in a 2 gal polyethylene jug. When I see the "under 1/2" message, I buy a gallon of distilled water at the grocery store and add it to the container. The next day it is completely dissolved. I pour it thru a fine mesh filter cap of my own design into the F350. We've consumed over 30 gallons of this DEF and no issues. In fact we use less DEF and get slightly better fuel economy with our DEF vs. Truck Stop. Why? Exactly 32.5% urea, and better NOx control so less EGR contribution.
They are welcome. Communication is GOOD for the RV community and DEF is here to stay. We are supporters of this forum, and would consider it a privilege to be your resource on the subject of DEF.