DEF Trucks
Custom DEF Trucks for Diesel Exhaust Fluid Transport
What are DEF Trucks?
In response to the Clean Air Act, diesel engines are required to use diesel exhaust fluid (DEF) in an effort to reduce these harmful emissions.
DEF is a system that helps convert nitrogen oxide (a dangerous emission) into harmless nitrogen and water. As a result, DEF trucks help reduce smog, acid rain, and air pollution.
On a DEF truck, the Diesel Exhaust Fluid is stored in a separate, insulated tank that typically has a blue cap. Diesel Exhaust Fluid is non-toxic and non-corrosive.
How Does DEF Work?
The fluid is sprayed into the exhaust steam of diesel vehicles to break down the nitrogen oxide. DEF is not a fuel additive and never comes in contact with diesel.
A Diesel Exhaust Fluid system does require a bit more room in your truck and adds slightly to the vehicle’s overall weight.
However, DEF trucks are designed for better fuel efficiency, more optimized combustion, and increased power. The Environmental Protection Agency (EPA) requires all vehicles capable of running with Diesel Exhaust Fluid to do so.
DEF Truck Tanks — What You Need to Know
The tank is the heart of any DEF truck, and getting the specifications right matters more than most buyers realize. Diesel exhaust fluid is sensitive to contamination — exposure to certain metals, dirt, or even small amounts of diesel fuel can render it ineffective and potentially damage your engine’s SCR system. That means the tank material, design, and construction quality aren’t just specs on a sheet. They directly affect the performance and longevity of your entire operation.
Tank Material
Stainless steel is the industry standard for DEF storage and the right choice for any serious operation. Unlike carbon steel or certain plastics, stainless steel does not react with diesel exhaust fluid, keeping the fluid pure and your SCR system protected. Osco Tank & Truck Sales builds DEF truck tanks from high-quality stainless steel to ensure your fluid stays uncontaminated from the moment it’s loaded to the moment it’s dispensed.
Insulated Design
DEF has a relatively narrow operating temperature range — it freezes at around 12°F and can degrade at sustained high temperatures. Proper tank insulation helps maintain stable fluid temperatures across a range of operating conditions, protecting your DEF supply in both cold winters and hot summers.
Tank Identification
DEF tanks are universally identified by a blue cap — an industry standard designed to prevent cross-contamination with diesel fuel. This color coding is an important safeguard, especially on job sites where multiple fluid types are in use simultaneously.
Capacity Options
The right tank size depends on your fleet’s daily DEF consumption and how frequently you can resupply. A smaller operation may need a modest tank for routine top-offs, while a large fleet or remote job site may require a high-capacity unit to minimize downtime. Osco builds DEF truck tanks in a range of capacities and can work with you to determine the right size for your specific needs.
Single vs. Double Compartment
Depending on your operation, a double compartment tank may allow you to carry DEF alongside another compatible fluid, maximizing the utility of a single truck. Osco can configure your tank to match your workflow and eliminate the need for multiple vehicles on site.
Why Choose Osco Tank & Truck Sales for Your DEF Truck?
When you’re investing in a custom DEF truck, the builder you choose matters just as much as the truck itself. At Osco Tank & Truck Sales, we’ve been building custom tanks and trucks since 1999 — and in that time, we’ve learned that no two operations are exactly alike. That’s why we don’t do one-size-fits-all.
Built to Your Specifications
Every DEF truck we build starts with a conversation. We work closely with you to understand your fleet size, daily DEF consumption, terrain, and budget, then engineer a truck that fits your operation rather than forcing your operation to fit a truck. From tank size and material to pump configuration and chassis selection, every detail is your call.
Quality You Can Count On
Our DEF truck tanks are built from high-quality stainless steel — the right material for the job — and engineered for long-term, trouble-free service. We don’t cut corners on materials because we know your operation depends on equipment that performs reliably, day after day and season after season.
A Partner, Not Just a Vendor
Osco is a family-owned business, and that shows in how we work with our customers. You’ll deal with real people who know trucks, answer your questions directly, and stay with you from the initial consultation all the way through delivery. We treat our customers the way we’d want to be treated — like family.
Nationwide Delivery
No matter where your operation is based, we can get your DEF truck to you. We’ve delivered trucks across the United States and into Canada, and we’ll make sure your unit arrives job-site ready.
Frequently Asked Questions About DEF Trucks
A DEF truck is a specialized vehicle designed to transport, store, and dispense Diesel Exhaust Fluid (DEF) — a non-toxic, non-corrosive fluid used in diesel engines to convert harmful nitrogen oxide emissions into harmless nitrogen and water. DEF trucks are essential for fleet operators, agricultural businesses, construction companies, and municipalities that run large diesel equipment and need a reliable on-site DEF supply.
DEF trucks use insulated tanks specifically designed to keep diesel exhaust fluid at a stable temperature and prevent contamination. Stainless steel is the preferred tank material for DEF storage because DEF can degrade when it comes into contact with certain metals, plastics, and other materials. Osco Tank & Truck Sales builds DEF truck tanks to the appropriate material standards to ensure fluid integrity and long tank life.
Tank size depends on your operation’s daily DEF consumption and delivery needs. Osco Tank & Truck Sales offers custom DEF truck builds with a range of tank capacities to match your specific requirements. Contact our team to discuss the right size for your fleet or operation.
DEF is non-toxic and non-corrosive, but it must be kept separate from diesel fuel at all times. DEF is never a fuel additive and should never come into contact with diesel. On a DEF truck, the fluid is stored in a dedicated, insulated tank — typically identified by a blue cap — to prevent any cross-contamination.
Any operation running multiple diesel vehicles or large diesel equipment that consumes significant amounts of DEF can benefit from a dedicated DEF truck. Common users include agricultural operations, construction and mining companies, municipalities, trucking fleets, and industrial facilities that need reliable on-site DEF delivery rather than depending on retail supply chains.
Yes. Osco Tank & Truck Sales builds every DEF truck to your specific requirements. Customization options include tank size and material, pump and metering systems for accurate dispensing, hose reels, chassis selection, and storage compartments. Whether you need a straightforward transport unit or a fully equipped mobile DEF dispensing system, Osco can build it.
Modern diesel vehicles equipped with Selective Catalytic Reduction (SCR) systems are designed to alert operators when DEF levels are low. If DEF runs out entirely, the vehicle’s engine power may be reduced or the vehicle may not restart, depending on the manufacturer. Having a dedicated DEF truck ensures your fleet always has access to a reliable supply on site.
