Nexgen DEF logo in white with yellow bar.

 Carson is the exclusive provider of NEXGEN DEF, the Northwest’s leader in diesel exhaust fluid.   


From 2.5 gallons to 10,000 gallons (or even more), we’ve got your DEF needs covered.


Explore on-site DEF storage options for your fleet. 

common def QUESTIONS

DEF is often misunderstood. Learn more about this important diesel fluid.


Certified Quality

Carson is proud to be the exclusive provider of NEXGEN DEF, the Northwest leader of diesel exhaust fluid. NEXGEN DEF is API-certified and made from the purest ingredients available on the market.

Package sizes

NEXGEN DEF is available in a range of package sizes, delivered to your door or available for will-call pick up at one of our 16 general branch offices or lubricant warehouses.


2.5 Gallons
1 Per Box


55 Gallons


275–330 Gallons


500+ Gallons

Storage Solutions

We offer a line of DEF pumps and storage options. All our tanks include internal heat elements to prevent freezing. We help you choose the right system for your business and facilities. 

Ask us about optional card-reader attachments. 


Attach to an existing tank.

Tank & dispenser

Self-contained tank in 350, 1000 or 1500 gallons with attached dispenser.

Portable Cubes

Self-contained DEF tank with attached dispenser for on-the-go applications.

Large DEF Tank

Self-contained tank with dispenser. Ideal for high-traffic stations & truck stops.

Frequently Asked Questions

Below are some of the most common questions about diesel exhaust fluid.

DEF is a non-toxic solution used in Selective Catalytic Reduction (SCR) systems to reduce harmful emissions from diesel engines. It is comprised of 67.5% deionized water and 32.5% synthetic, automotive-grade urea.

DEF plays a significant role in reducing nitrogen oxide (NOx) emissions, with an average reduction of about 90%. DEF is injected into the exhaust stream, reacting with nitrogen oxides (NOx) to convert them into harmless nitrogen and water vapor, reducing emissions and meeting environmental standards. This substantial decrease in harmful pollutants helps modern diesel engines comply with emission regulations and minimizes their environmental impact.

SCR is the dominant technology used by manufacturers to lower greenhouse gas emissions without compromising engine efficiency and power. It is found on most modern diesel-powered heavy and medium duty trucks, equipment and some passenger cars.  While SCR technology has existed since the 1950s, it became more prevalent in diesel engines produced after 2009 as manufacturers made changes to meet stricter air quality standards set by the Environmental Protection Agency.

Yes, DEF is non-toxic, non-hazardous and safe. While non-toxic, urea is a fertilizer and can contribute to algae blooms in natural water systems. Promptly clean any DEF spills to prevent run-off contamination.

The consumption rate varies, but as a general guideline, DEF consumption is around 2-3% of diesel fuel consumption. Most vehicles have a DEF gauge to monitor levels.

Yes, DEF can freeze at temperatures below 12°F (-11°C), so store DEF in a warm, dry location away from sunlight. Carson also offers temperature-controlled DEF tanks which are suitable for outdoor settings. Should your DEF freeze, however, it thaws without any loss of performance once temperatures rise.

No, Diesel Exhaust Fluid (DEF) does not hurt engine performance. In fact, it contributes to improved engine efficiency by helping diesel engines meet emission standards. Running out of DEF, however, may result in reduced engine performance or speed limits, so it’s crucial to monitor and refill as needed.

Like it does with your fuel system, your vehicle should warn you when DEF levels are low. If DEF is not added before it reaches critical levels, the engine’s electronic control module may reduce engine performance or implement speed limits.

DEF has a shelf life of 12 months; store in a cool, dry place away from sunlight.

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