What is DEF and why is it important to your diesel fleet? Featured Image

What is DEF and why is it important to your diesel fleet?


In the dynamic landscape of modern transportation and industrial sectors, the pursuit of cleaner and more environmentally responsible technologies has never been more imperative. As governments and industries worldwide grapple with the challenges of reducing harmful emissions and safeguarding air quality, Diesel Exhaust Fluid (DEF) emerges as a pivotal solution. This innovative additive, a precise blend of urea and deionized water, holds the key to transforming diesel engines into efficient, eco-friendly powerhouses.

What is DEF?

DEF, or Diesel Exhaust Fluid, is made of 32.5% urea and 67.5% deionized water. Urea is a chemical compound naturally produced in animals and humans. It is also synthetically produced for use in industrial applications, including DEF.

How does it work?

When DEF is injected into the exhaust stream of a diesel engine, it reacts with hot exhaust gases to convert nitrogen oxides (NOx) into harmless nitrogen and water vapor. NOx is a major component of smog and can also contribute to acid rain and global warming. By reducing NOx emissions, DEF improves air quality and protects the environment.

Why is it important?

DEF is important for diesel engines because it helps them to meet strict emissions standards put in place by the Environmental Protection Agency (EPA). In the United States, all new heavy-duty diesel vehicles manufactured after 2010 are required to use DEF. Medium-duty diesel vehicles are required to use DEF starting in 2014.

What benefits do DEF provide to an engine?

While DEF is primarily used for emissions control, it can also improve engine efficiency and performance. By optimizing combustion and reducing the formation of NOx, engines can operate more efficiently, potentially leading to improved fuel economy and power output.

  • It helps to keep the engine’s exhaust system clean. DEF helps to prevent the buildup of soot and other deposits in the exhaust system. This can help to improve fuel economy and engine performance, and it can also extend the life of the exhaust system.
  • It helps to prevent engine damage. The buildup of soot and other deposits in the exhaust system can cause damage to the engine. DEF helps to prevent this damage by keeping the exhaust system clean.
  • It can improve fuel economy. DEF-equipped engines typically get better fuel mileage than those without DEF. This is because DEF helps to keep the engine’s exhaust system clean and free of deposits, which can reduce drag and improve efficiency.

What is the replacement interval?

DEF consumption is typically around 2-3% of diesel fuel consumption. However, this can vary depending on factors like engine load, temperature, and driving conditions.DEF should be replaced every 20,000 to 30,000 miles. The exact interval will vary depending on the vehicle. DEF is not compatible with all diesel vehicles. If you are not sure if your vehicle requires DEF, check the owner’s manual.

If you own a diesel engine that requires DEF, it is important to keep the DEF tank full. If you run out of DEF, your engine will go into limp mode and you will not be able to drive it until you refill the DEF tank.

To learn more about DEF and other oils, lubricants, and chemicals Gaubert Oil offers, contact one of our expert team members.