What is DEF? Diesel Exhaust Fluid Guide
DEF (Diesel Exhaust Fluid) is a non-toxic solution of 32.5% automotive-grade urea and 67.5% deionized water. It is injected into the exhaust stream of modern diesel engines equipped with SCR (Selective Catalytic Reduction) systems to convert harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor.
How It Relates to Fuel Delivery
All diesel engines manufactured since 2010 for on-road use (and since 2014 for off-road/Tier 4) require DEF to meet EPA emissions standards. Without DEF, these engines will enter a 'limp mode' that severely limits power and speed — a critical issue for fleets and construction operations.
DEF consumption is typically 2-3% of diesel consumption. So if a truck burns 1,000 gallons of diesel per month, it will use approximately 20-30 gallons of DEF. Bulk DEF delivery is far more economical than purchasing jugs from retail locations — and ensures you never run out.
DEF must be stored properly — it degrades above 86°F and freezes at 12°F. It has a shelf life of about 12 months when stored correctly. BettyJet delivers ISO 22241-certified DEF in totes (275 gallons) or bulk tanker loads and can advise on proper storage solutions.
Why It Matters for BettyJet Customers
Running out of DEF shuts down your diesel equipment. BettyJet delivers DEF in bulk directly to your site — totes or tanker loads — at prices well below retail. We can set up scheduled deliveries so your DEF tank never runs dry.
Frequently Asked Questions
What happens if I run out of DEF?
Modern diesel engines will progressively reduce power and eventually enter 'limp mode' if DEF runs out, limiting speed to about 5 mph. The engine won't be damaged, but your equipment will be essentially unusable until DEF is refilled.
How much DEF does a diesel engine use?
DEF consumption is typically 2-3% of diesel fuel consumption. A truck using 1,000 gallons of diesel per month will use approximately 20-30 gallons of DEF. Bulk delivery from BettyJet is far more cost-effective than buying retail jugs.
Related Terms
ULSD stands for Ultra-Low Sulfur Diesel — a cleaner-burning diesel fuel containing no more than 15 parts per million (ppm) of sulfur. Since 2006, the EPA has required all on-road diesel sold in the United States to meet the ULSD standard, replacing Low Sulfur Diesel (LSD) which contained up to 500 ppm of sulfur.
Dyed DieselDyed diesel — also called red diesel or off-road diesel — is standard ULSD fuel that has been dyed red to indicate it is exempt from federal and state road taxes. It is chemically identical to on-road diesel but costs significantly less because the tax (typically $0.40-0.60/gallon) is not applied.
Wet HosingWet hosing is the practice of fueling vehicles or equipment directly from a mobile fuel truck rather than from a stationary storage tank. The fuel truck pulls up to each vehicle and fills it on-site — no bulk tank, no pump, no infrastructure required.
Ready to Order Fuel?
Get a competitive quote for diesel, gasoline, jet fuel, DEF, or marine fuel delivered anywhere in Florida.