DEF, answered plainly
What DEF is, how to size and store it, how delivery works, and how to run your account — without the chemistry wall.
Understanding DEF
What is DEF?
Diesel Exhaust Fluid (DEF) is a precise mix of 32.5% high-purity urea and 67.5% deionized water. It is injected into the exhaust of modern diesel engines, where it breaks down harmful nitrogen-oxide (NOx) emissions into nitrogen and water. It is not a fuel additive and never goes in the fuel tank — it has its own separate tank.
Why does my equipment need DEF?
Virtually every 2010-or-newer diesel engine uses a Selective Catalytic Reduction (SCR) system to meet EPA emissions rules, and SCR runs on DEF. Without it, the engine will derate power and eventually will not start — no DEF, no run. Keeping DEF topped off keeps your equipment both working and legal.
What is SCR and how does DEF fit in?
Selective Catalytic Reduction is the after-treatment system that cleans diesel exhaust. A fine mist of DEF is sprayed into the hot exhaust stream ahead of the catalyst; the urea reacts with NOx and converts it to harmless nitrogen and water vapor. DEF is the consumable that makes SCR work.
Does DEF quality actually matter?
Yes. Off-spec or contaminated fluid can clog injectors and damage the SCR system — an expensive repair. We deliver ISO 22241 spec-grade DEF so what reaches your tank protects your equipment and keeps you compliant.
How should DEF be stored, and does it expire?
Store DEF between roughly 12°F and 86°F, out of direct sunlight, in an approved container. Kept properly, it has about a one- to two-year shelf life. It freezes around 12°F but is unharmed — it simply thaws back to spec. Our totes and tanks are built for safe, clean storage.
Buying & sizing
Totes or a bulk tank — which do I need?
It comes down to throughput and space. A 330-gallon tote is the workhorse for steady job-site and yard demand; a 180-gallon Eco-Tote fits tighter sites and lower usage; bulk tanks (500–2,000+ gal) make sense for high-volume fleets and terminals. Tell us your gallons and sites and we will size it — no over-buying.
How much DEF does my fleet use?
A useful rule of thumb: DEF consumption runs about 2–4% of diesel used. So a truck burning 100 gallons of diesel uses roughly 2–4 gallons of DEF. Heavy idling and hard work push it higher. Share your diesel volume and we will estimate your DEF demand and the right delivery cadence.
What does DEF delivery cost?
Pricing depends on volume, container type, delivery frequency, and location — higher volume and recurring routes bring the per-gallon cost down. We quote it plainly with no surprise fees. Request a quote with your usage and service address and we will put real numbers in front of you.
Is there a minimum order or contract?
No long-term contract is required to get started. We work with operations of every size — order on-demand or set up a recurring route, and scale up or down as your needs change.
Delivery & logistics
Where will you deliver?
Wherever product is needed — job sites, company yards, or directly to vehicles on the road. We fill bulk tanks, top off totes in place, or fill equipment directly. We meet you at your door.
How do I schedule a delivery?
Set a recurring route that matches your burn rate, or order on-demand as you go. Existing customers can also schedule and track everything in the customer portal. New to us? Request a quote or call 888-280-5611 to get set up.
How fast can you deliver?
Most new accounts in our core New Jersey markets get a first delivery within a few business days, and recurring routes are planned around your schedule. Tell us your timeline and we will work to it.
What areas do you cover?
All of New Jersey, plus the greater Northeast for regional accounts. See our service-area page for county-by-county coverage and dedicated pages for our busiest markets.
How do you keep me from running out?
Add tank monitoring and we track your usage in real time, topping you off before you hit empty. That cuts unnecessary trips, prevents run-outs and derates, and gives you clean data to budget against.
Customer portal
What can I do in the customer portal?
The portal gives you secure electronic access to every delivery, gallon of usage, and invoice in one place — plus scheduling. Information is power, and it should be in your hands. Paperwork shouldn’t be hard, so we’ve made it easy.
How do I get access?
Every DEF Express customer gets a portal account. If you have not set yours up, reach out and we will get you logged in — or use the Customer Portal link in the header to sign in.
Can I see and pay invoices online?
Yes. Your invoices, open balance, and payment history all live in the portal, so billing and reporting stay simple and audit-ready.
Can I pull usage reports for budgeting?
You can view gallon usage over time and download reports — useful for budgeting, allocating cost across sites, and emissions reporting.
Still have questions?
Talk to a real person — no phone tree. We’ll size the right solution with you.