In 2010, the Environmental Protection Agency (EPA) announced that all diesel engines are required to use a selective catalytic reduction (SCR). SCR is powered by a consumable fluid called diesel exhaust fluid (DEF) which is composed of deionized water and a pure form of urea (composed of nitrogen, hydrogen, carbon and oxygen). Together, DEF and SCR increase fuel efficiency and reduce emissions.
How does SCR and DEF work?
Exhaust gas is routed from the engine through a particulate filter to remove soot and ash generated from burning diesel. The exhaust gas then moves past a nozzle that sprays DEF into the stream of gases. The exhaust gas then enters the catalytic converter where nitrogen dioxide and monoxide is converted to nitrogen and water.
Why do trucks need DEF?
Unlike gasoline-powered vehicles, diesel-powered vehicles release exhaust with more pollutants such as nitrogen oxides. DEF helps to clean up the exhaust before it is released into the air.
How often do you need to fill up with DEF?
Trucks should be refilled with DEF about as often as getting an oil change. DEF is sold at every truck stop and is relatively inexpensive since it is made of simple ingredients.
A few things to be aware of . . .
The 2019-2020 winter is predicted to be especially cold in the eastern parts of the Rockies and the region east of the Appalachians. For truck drivers, cold weather poses certain risks to DEF. When frozen, DEF will expand up to 7% and can damage storage tanks that are full or nearly full. To prevent damage, keep tank levels less than full and avoid adding any additives to thaw DEF.
DEF typically has a shelf life of 12 months. Before purchasing DEF, check the expiration date and look for the American Petroleum Institute (API) certification mark. Avoid storing DEF containers for too long and exposing them to extreme heat or sunlight.