Looking to buy a new diesel pickup? The Big Three truck makers would sure like to make you a deal. And this year, thanks to a federal mandate, the stuff blowing out of the tailpipes of these new rigs is much lower in nitrogen oxide (NOx). This is good news for the environment, but for owners of 2010 (and later) diesel burning vehicles, there will be one more detail to look after: Your rig will most likely have an additional fluid to keep topped off—diesel exhaust fluid (DEF). Are you ready?
How it Works
We’ve all heard the complaints about “smelly diesels.” Happily the odor issue isn’t as big as it once was, but admittedly diesels do add their own share of pollutants. NOx contributes to acid rain, respiratory health problems and global warming. Look out over that beautiful skyline and find your vision obscured by smog? NOx is a major contributor. Uncle Sam mandated that truck manufacturers reduce diesel NOx emissions by 90 percent in 2010 from the previously allowable levels.
To reduce NOx, engine manufacturers hit on two approaches: One calls for a major overhaul of the old exhaust gas recirculation (EGR) system, the other is through a process called selective catalytic reduction (SCR). SCR proponents say it’s more fuel-efficient than the EGR makeover, and GM, Ford and Dodge have all jumped on the SCR bandwagon for their 2010 diesel trucks.
How does the SCR system work? In the typical Cummins system exhaust gases pass out of the exhaust manifold and head downstream into a particulate filter. The filter snags many of the nasty little particles associated with respiratory problems. From there the cleaned-up gases head into a new device called a decomposition reactor. This reactor shoots a fine spray of a liquid called DEF (diesel exhaust fluid) into the exhaust stream. The cooled and moisture-enriched exhaust then streams into an SCR catalyst. After passing through the catalyst, the NOx-reduced exhaust gas passes through the muffler system and out into the atmosphere. Along the way, the original heavy load of NOx has been converted into its basic components of nitrogen and water. Nitrogen is naturally produced in the environment, and is a basic building block used by plants, and of course, everybody likes water.
But what about that DEF that is squirted into the exhaust gas stream? Glad you asked. DEF is a mixture of about two-thirds deionized water and one-third purified urea. Urea? Yeah, urea is a natural “waste byproduct” but happily it’s often produced synthetically without a nasty odor. It’s used in the conversion process because when urea runs through the decomposition reactor, it converts into ammonia. The latter mixes with the NOx from the engine’s exhaust, and that’s what causes the changeover from NOx to simple nitrogen and water.
What About You?
For truck owners with SCR systems, obviously there is going to be a cost. Just how much the price of a new truck has been hiked to account for the additional technology isn’t clear. But “down the road costs” will need to be accounted for. For every gallon of diesel fuel burned, a given amount of DEF will have to be pumped into the system. How much will this add to your travel costs? Typically you’ll need about 2 percent DEF per gallon of diesel burned. For example, the owner of a pickup that runs 12,000 miles a year, averaging 15 miles per gallon, would use about 16 gallons of DEF a year. Buying it in gallon containers, you could expect to add about $95 to your annual budget, based on the current price of DEF at Pilot truck stops.
Truck stops are gearing up to sell DEF at the pump. Pilot Travel Centers already have pumps in 100 of their locations across the country and say they plan to add more into next year. Getting your DEF directly at the pump has its drawbacks, of course. You’ll need to find a center convenient to your travels. On the other hand, buying DEF and holding onto it has its own set of problems: DEF does have a shelf life, and is affected by temperature. DEF must be stored at temperatures of less than 80 degrees. In that temperature range, it is said that DEF will degrade after six months. For those living in warm climates, storing DEF calls for leaving it in an air-conditioned environment. On the other hand, below 12 degrees Fahrenheit DEF gels and won’t pump. Hence, truck manufacturers are having to handle the problem by keeping DEF containers built into your truck warm.
Since DEF isn’t going to be as readily available as diesel itself, it will pay to stay up on your DEF levels. We made random calls to truck dealerships inquiring about DEF availability. While the salesmen themselves suggested they were versed on DEF for the rigs they sold, 100 percent of the parts countermen at those same dealerships told us they didn’t have it available, and many didn’t even have a clue as to what DEF is.
Some have wondered if it might just be easier to let the DEF tank in their rig run dry and ignore the situation. Most manufacturers have got that covered: Get low on DEF and an idiot light on the dash will begin nagging. Run out of DEF completely? You may find your engine goes into “limp mode” with resultant loss of horsepower until the tank is refilled. Others may simply “lock out” and not allow the engine to start up. Either way, driving without DEF isn’t an option.
Kermit the frog was wont to say, “It isn’t easy being green.” For 2010 diesel truck and RV owners, his sentiment may become the new slogan.
Russ and Tiña De Maris are authors of RV Boondocking Basics—A Guide to Living Without Hookups, which covers a full range of dry camping topics. They also provide great resources in their book, Camp Hosting USA—Your Guide to State Park Volunteering. Visit www.icanrv.com for more information.
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