In the United States, all vehicles using diesel engines must comply with the emission and particulate pollutant requirements of the Environmental Protection Agency (EPA). Most manufacturers use selective catalytic reduction (SCR) and diesel exhaust fluid (DEF) to meet these requirements.

This process removes nitrogen oxides (NOx) from the exhaust gases. To do this, a catalyst and a reducing agent are used. The use of this technology is essential to comply with environmental regulations.

DEF is used in selective catalytic reduction to reduce harmful emissions. For example, it is injected into the exhaust system to break it down into ammonia and water.

Ammonia interacts with nitrogen oxides and transforms them into water vapor and nitrogen, gases that are less harmful to the environment.

What is diesel exhaust fluid (DEF)?

It can be defined as an aqueous solution composed of demineralized water and 32.5% high purity urea. The main function of this fluid, which is also known as UREA, is to reduce harmful emissions generated by diesel engines.

What is DEF

As we have just seen, diesel exhaust fluid is injected into the exhaust system of vehicles. There that it is broken down into ammonia and carbon dioxide, elements that interact with the nitrogen oxides in the exhaust gases to convert them into less environmentally harmful ones.

This process is essential to comply with environmental regulations on diesel vehicle emissions. It should be noted, however, that DEF is not mixed with diesel fuel. It is actually stored in a separate tank and is consumed at a much lower rate.

6 benefits of API Diesel Exhaust Fluid Certification

The main guarantees offered by API diesel exhaust fluid certification are:

  • It allows you to know which diesel exhaust fluids meet all the requirements issued by the manufacturers.
  • It makes it easier to locate the fluids for purchase and use.
  • It guarantees that the user can always buy fluids from top brands and of the highest quality.
  • Allows a comparison between the different diesel exhaust fluids available on the market.
  • Reduces nitrogen oxide pollutant emissions.

Diesel exhaust fluid and nitrogen oxides

  • The consumer will always have a perfectly approved licensed fluid at his disposal.

If you wish, you can download the overview of the Diesel Exhaust Fluid Program here. A PDF document in which you can obtain more information and learn about its main requirements.

As suppliers of the best lubricant products in Puerto Rico, do not hesitate to acquire with us the lubricants and fuels that your equipment needs. You can write us at any time at or call us at (787) 794-1985.