Watch for expiration dates, quality when buying DEF, says API

Closeup of semi
The American Petroleum Institute advisees truck owners to use caution when purchasing and storing diesel exhaust fluid (DEF).

The list of ways in which the COVID-19 pandemic has impacted trucking is a long one, but there’s one impact in particular that drivers should be aware of, according to a release from the American Petroleum Institute (API). The group is advising truck owners to use caution when purchasing and storing diesel exhaust fluid (DEF).

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The group is reminding DEF users that the product has a useful life that can be shortened by adverse conditions, such as heat. Even under good conditions, the shelf life of DEF is about 12 months, maybe a little longer if storage conditions are optimum. DEF stored at 86 degrees and above will last only six months or so, according to API.

Drivers who normally purchase DEF at truck-stop fuel pumps probably won’t need to worry, unless the truck stop has been closed down for a long period of time. It’s the packaged stock that could be a problem. Convenience stores and other retail outlets that have shut their doors for weeks or even months may have product on the shelves that has reached its expiration date.

Additionally, DEF that has been stored in an area exposed to heat, such as an outdoor shed or an exposed storage box on a truck, can degrade faster.

API recommends drivers make sure they note the manufacturer of the DEF they purchase. Some states require that the manufacturer be listed on the receipt, but not all.

Drivers should check for an expiration date on the package, too. If there isn’t one, there may be a traceability code that contains a packaging date. Adding 12 months to this date will provide an approximate expiration date.

As for DEF that has already been purchased, drivers should check for dates on their supplies. The package often has recommended storage temperatures printed on it. Side boxes on trucks usually aren’t well insulated and can get much warmer than cab and sleeper areas, while frame- or catwalk-mounted boxes can get very warm. If in doubt, the product should be replaced with fresh DEF.

Exposure to direct sunlight can also cause DEF to degrade faster.

DEF that has aged past its shelf life or has gone bad due to heat or sunlight exposure can cause problems with components of the selective catalytic reduction (SCR) system, such as the DEF dosing pump or the diesel particulate filter (DPF), leading to downtime and repair expense. Warranty coverage may be denied if bad DEF is identified as the cause of the failure.

Diesel engines can also “derate” if bad DEF is detected. This condition will result in loss of power and speed but should allow the engine to run long enough to get to a repair facility.

Drivers should responsibly discard DEF that is past its expiration date or that appears cloudy or dirty. More importantly, drivers should be aware that the age of the DEF they use is important and should buy and use only fresh, high-quality DEF. API recommends that drivers inspect packaging for the phrase, “API licensed” or similar wording to ensure high quality.

API also cautions drivers that there is no additive that improves the quality of DEF; adding anything to the fluid could reduce its effectiveness or even cause damage.

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