Diesel Exhaust Fluid Quality Matters

Why should you care about DEF Quality?

The emission system installed on your vehicle is a very expensive and precise configuration of fluid control, sensors, filters, precious metal catalyst and heaters. For long term, maintenance free operation of your emission system the critical determining component is the diesel exhaust fluid (DEF). Although DEF is considered a simple configuration of high purity urea and deionized water DEF can be easily contaminated causing costly repairs.

Where is your diesel exhaust fluid coming from?

DEF can be produced through a blending process which combines 32.5% high purity urea – a nitrogen base widely used in fertilizer – with 67.5% de-ionized water.

Blending uses high-purity granules (prill) blended with high-purity water. The urea is highly soluble and non-toxic, which makes the blending process so simple. It's absolutely crucial to know where Diesel Exhaust Fluid is coming from before it reaches your tank. The simplicity to produce DEF generates concern in the market since any trace of contamination can lead to a costly fix.

Read more about the risk of DEF blenders

The risk in compromising quality

If Diesel Exhaust Fluid is not handled properly, there's potential for major problems including:

  • Voided vehicle warranties
  • Premature catalyst deactivation
  • Detrimental effects to SCR performance
  • Lower fuel economy
  • Fouled pre-filters & injector nozzles

Handling DEF: Do's and don'ts

  • Do periodically clean the pump nozzle after filling by dipping the nozzle into a tub of clean water.
  • Do avoid overfilling; DEF can be difficult to clean up if spilled on the vehicle, dispenser or floor.
  • Do only use dedicated pumps, tanks, containers and delivery equipment for DEF.
  • Do only use designated equipment designed for use with DEF.
  • Do educate drivers and mark tanks on trucks to ensure DEF is not added to diesel fuel.

  • Don't ever add DEF to the diesel fuel.
  • Don't use DEF from suppliers who do not adhere to ISO standards.
  • Don't use discolored DEF.
  • Don't use DEF with visible particles floating in the fluid.
  • Don't allow DEF to contact equipment containing materials such as copper, iron, zinc, aluminum or magnesium.
  • Don'twait to clean up spilled DEF; it should be cleaned up as soon as possible.

DEF is tested in-house before it reaches your tank

Our DEF is tested for quality from alkalinity to urea content at each of our locations, during repackaging, and before the fluid is delivered to our customers. We're the ONLY North American DEF distributor with in-house lab quality testing which includes:


Testing for DEF quality & concentration.


Testing to all 18 DEF parameters by ISO 22241.

3 Easy DEF testing methods

Quality is of the utmost importance when handling and delivering Diesel Exhaust Fluid (DEF). We'll take you through three proper ways you can test DEF quality.

You can examine your DEF by visually checking for clarity, ensuring there are no contaminants or debris floating in the fluid. This will only check for color and debris in the product that could potentially clog filters on the SCR system. If the DEF is any color but clear, you may have a problem with mineral contamination. This method will not provide the concentration of urea to water or any mineral contaminates.

You can use a handheld DEF Chek Tester or purchase an electronic handheld refractometer like the Misco DEF-201 at a cost of around $360. This will measure the concentration specifications of the fluid to ensure 32.5% of the fluid is urea. If using the DEF Chek Tester, you will fill the tester to the designated line then read number of floating discs which displays the urea concentration of the fluid. If none, 1 or 3 discs are floating then you should replace your fluid.

  • 0 Discs < 29% Urea Concentration
  • 1 Disc 30% Urea Concentration
  • 2 Discs 32.5% Urea Concentration
  • 3 Discs 35% Urea Concentration

You can send samples of your DEF to an outside lab. Most lab tests will measure everything to the ISO 22241 specification, debris, concentration and the presence of any contaminates. This costs roughly $800 per sample.

Contact us for more information

Contact us today by completing the short form to find out more about our specialty chemical product line, or if you have a question about our DEF products.