Important Things to Know about Winterizing Your Diesel Exhaust Fluid (DEF)

It's amazing how timeless some ideas are. Change is the one constant in life. Nothing remains the same forever, or so it seems. This is especially true in the realm of technology. In the past few decades we've seen nanotech applied to filters, and "brain boxes" (minicomputers) orchestrating the symphony of movements within the internal combustion engine. 

Many of these technical improvements are driven by a singular aim: the more efficient production of power while simultaneous producing cleaner outcomes. 

When the EPA in 2010 mandated selective catalytic reduction (SCR) in diesel trucks, the objective was clearly positive for the environment, but appeared to be problematic for the consumer. Why? Because it violated the principle of KISS--Keep It Simple Stupid--by adding a step to our maintenance regimens. The added complication was the need for Diesel Exhaust Fluid (DEF).

Like most habits, as it turns out, maintaining DEF has not been as big a headache as initially perceived. It's no more complicated than making sure your truck has wiper fluid. Nevertheless, there may have been some gripes till we got used to it, and having a dashboard warning indicator there to remind us our DEF was low was also helpful and wise.

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ALL THIS TO SAY that as we head into the most frigid time of year if may be a good time to be reminded about winterizing and DEF. Here are some insights from an article by K.J.Jones at last winter's Truck Trend site, "Tips for Handling and Storing DEF in Cold Climates."

Early in the article Jones explains, "Handling and storing DEF in cold climates can be challenging. Made from a mixture of technically pure urea and purified water, DEF freezes at 11 degrees Fahrenheit and needs to be properly maintained and dispensed to preserve its quality."

A lot of people may forget that DEF is two-thirds water and water freezes when it gets cold. In other words, you shouldn't store the DEF in an unheated garage or in the back of your pickup if you live in North Dakota or Upper Michigan.

Because water expands when it freezes, you should not fill the DEF tank all the way in winter, Jones says. Some trucks have low-energy heaters that will protect the fluid from freezing during shutdown, but if you aren't sure about yours, this would be a word to the wise. 

IF YOUR DEF FREEZES, do not put additives in the tank to help it melt, says Jones. The DEF fluid needs to be kept pure to work properly. Instead, there there's a special heater that will melt the DEF fairly quickly. 

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SHELF LIFE is a consideration to keep in mind when storing and handling DEF. Wine may get better with age, but DEF does not. You should make sure to note the expiration date on your bottle, usually one year or a little longer under optimal conditions.

DEF is manufactured to certain specifications which get approved by the API. Jones suggests looking for the API approval logo on the package. There are also a few additional statements about storage conditions. Not only do you want to keep it from freezing, you also shouldn't let it sit in the sun if your in Miami next summer. 

To review the full article, visit:
http://www.trucktrend.com/news/2001-winterize-diesel-exhaust-fluid-def
How to Winterize Diesel Exhaust Fluid (DEF) 

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EXTRA POINT: How DEF Works
DEF is made from deionized water and a very pure form of urea. When hot exhaust gas and DEF enter the catalytic converter, the urea from the DEF and the exhaust gas reacts with a variety of metallic compounds to convert nitrogen dioxide and monoxide into harmless nitrogen and water.