Friday, January 26, 2018
Breaking News


By Tony Sippel, RV product manager at Freightliner Custom Chassis Corporation


As vehicles meeting 2010 EPA emissions requirements are hitting the market, Freightliner Custom Chassis Corporation (FCCC) has begun to receive feedback from our motorhome dealerships and potential customers. We’ve noticed that people are often confused about what exactly diesel exhaust fluid (DEF) is, how it works and how it fits into the Selective Catalytic Reduction (SCR) technology.


DEF is a solution stored in a tank, which is injected into the exhaust stream, reacting with the Nitrous Oxide (NOx) in the SCR catalyst, forming harmless nitrogen and water. Let’s take a moment, though to further dispel the myths and fully answer questions regarding DEF.


MYTH: SCR technology does not meet EPA 2010 emissions regulations.

FACT: The EPA has approved SCR technology for 2010 emissions regulations. SCR technology is a long-term solution, working to reduce fuel consumption directly tied to carbon-dioxide emissions and significantly decreasing the amount of noxious gasses in the exhaust.


MYTH: DEF is corrosive, hazardous and unsafe to handle.

FACT: DEF is two-thirds water. It is an organic, nontoxic compound made of 32.5 percent urea and 67.5 percent de-ionized water. DEF is carefully regulated by the American Petroleum Institute. Also, urea solution is not flammable and is not deemed “hazardous” by any United States or Canadian transportation authority.


MYTH: Urea becomes toxic at 118 degrees Fahrenheit.

FACT: According to James Spooner, vice president and general manager at Colonial Chemical Company, urea does not become toxic at any temperature. At 122 degrees Fahrenheit, DEF will still meet ISO specifications of less than 0.2 percent ammonia for at least 35 days. At that rate, it would take more than two years to reach the ammonia level of household ammonia, which obviously is not classified as toxic.


MYTH: DEF solution is a significant added expense for vehicle owners.

FACT: The industry is expecting the cost of DEF solution to be parallel with the price of fuel, fluctuating between $2.50 and $3.50 per gallon. Just 2.5 gallons of DEF will yield more than 800 miles of travel. FCCC uses 10 and 13 gallon tanks. Drivers should expect to refill their DEF tank three times a year. Also, through extensive testing, Cummins Engine realized a 5 percent to 9 percent fuel economy advantage with SCR over the alternative in-cylinder EGR solution, which amounts to significant savings over time.


MYTH: Refilling the DEF tank is a hassle for vehicle owners.

FACT: The DEF tank is as easily accessible to drivers as the gasoline tank. Think of it this way:  Refilling your DEF tank is like refilling your windshield wiper fluid. It’s something that is completed a few times a year, taking no more than five or 10 minutes.


With so many myths out there, it’s easy to see why motorhome dealers and drivers have questions about DEF and SCR technology. We hope this has helped clear up any confusion on the topic you may have experienced. If you do have questions or would like more information about DEF and SCR technology, please visit or post your questions here, and I’ll be sure to follow up with you.


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About Greg Gerber

Greg Gerber is a freelance writer and podcaster who has been writing about the RV industry since 2000. He is the former editor of RV Daily Report.


  1. You can avoid all of the hassles with the DEF and SCR by just purchasing an RV with a Navistar MaxxForce engine that uses EGR technology instead of the SCR solution. You will avoid the extra weight on your vehicle from the SCR components and avoid the hassle of having to use DEF in the first place. Better yet, why not look into the new Monaco Vesta, which has the MaxxForce engine and has been wind tunnel tested to improve overall fuel economy?

  2. There is more than one reason why the overwhelming majority of RV manufacturers, and commercial truck manufacturers, are using SCR technology with DEF. In fact, only one manufacturer in the entire industry, Monaco/Navistar is not using this technology, instead opting for extreme EGR. Not an exhaustive list but some of the reasons the significant majority of OEM’s will be using SCR with DEF are the following:
    1. Proven technology – DEF is already being used in hundreds of thousands of vehicles over hundreds of millions of miles in Europe. We’re not aware of any vehicles racking up equal miles with the Extreme EGR technology.
    2. Improved fuel economy – Customers will see 5-8% fuel economy improvement, making up for the cost of the DEF and then some. Regardless, we look forward to getting our hands on a MaxxForce with 2010 technology; however we have yet to locate one for sale in the market. Meanwhile, Cummins has produced over 25,000 engines, including for RV use, with EPA 2010 technology which can already be found in trucks and RV’s on dealer’s lots or in customer’s hands.
    3. With the SCR/DEF solution, we are able to provide increased horsepower and torque without increasing engine displacement.
    4. Simple solution – Consumption rate of DEF to fuel is approximately 2%. If you run 10,000/year you’ll need to fill up your DEF tank 3-4 times per year. Fill up is as hassle free as filling up your windshield washer fluid and provides the benefits above while meeting the stringent EPA guidelines.

    As the blog says, see for yourself about these benefits and more at the facts about SCR website mentioned in the post.

  3. Tony,
    As rosey as you try to make this sound…… forget to mention some of the cons to this system. This secondary tank can only be filled at truck stops or dealers. From everything I have read, you will burn 1 gallon of this to every 66 gallons of fuel. So the customer making a massive cross country trip may find this to be a little interesting. Especially if they are averaging 10 miles per gallon. This fluid will freeze at cold temperatures and is ruined at high temps. So people in the Southwest or North are in trouble. Considering the safety meaurements taken to make sure that someone does not let their tank run dry – those procrastinators will be able to drive a whopping 5 miles per hour to find that truck stop on the Alaskan Highway for a fill. Now I only know what I have read……If I am wrong I am sorry…..but this technology does not sound all rosey and wonderful. I will gladly run all our old technology diesels till they are dead……rather than have to deal with this!

    • More than one of your myths are wrong it apparently that you don’t drive a diesel and don’t have to buy this way over priced crap Chevy and Gms you have to open the hood and it is way across on the passenger side of the truck who ever said that it would not affect fuel mileage is an idoit and does not know what the hell he or she is talking about my consumption of this crap is way too much with the added cost of this crap with diesel y’all can keep it I’m with the guy above shove it up you backside

  4. . . . and then there’s the original cost.

  5. In response to the post by “Seriously” – thanks for the comments, they echo much of the misunderstanding about DEF. First, let me say we’ve been using this technology in Europe for several years now, over hundreds of millions of miles, and it gets very hot and very cold there as well and they’ve had no issues. Yes, DEF does freeze (It’s 66% water). However, the tank is heated and the fluid begins to defrost immediately. The motorhome performance won’t be affected and you can jump right in and head down the road without delay. It may also experience some slight degradation in direct sunlight and intense heat – think 120F for prolonged periods of time. It will not be exposed to either. The tanks are protected and covered by the coach, and even in Death Valley, temperatures drop below 120F at night. Procrastinators will experience a derate after ignoring numerous warnings over 500-700 miles (that’s a lot of procrastination!). The derate is a loss of horsepower, but not enough to put anybody in danger. You’ll still be able to go 55 mph in order to get to a location that sells DEF. Which, by the way, can be truck stops or dealerships, but also auto parts stores and even big box retailers like WalMart? DEF will be sold in gallon jugs and can be carried on the coach just like windshield washer fluid. So there’s no reason for anybody not to have access to DEF, even in Alaska.

  6. Our new Freightliner uses a gallon of DEF about every 1200-1400 miles. It’s going to be more than "a few times a year" to fill. A 2.5 gallon jug costs us about 12 dollars, so more expensive than diesel fuel, which some have said that’s all it would cost.
    It will turn out to be an expensive add-on to our operating costs, and I am not convinced the perceived "savings" in fuel economy will make up for it. Plus, what happens if this system breaks down? Truck won’t run. Anyone have experience in repairs or service on this system?

  7. Another way all this confusion can be avoided is by purchasing a new Dodge Ram HD instead of any Ford or Chevy. Dodge found a way to pass the stringent emissions law in 2007 without the use of any additional fluids.

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