DEF | Diesel Exhaust Fluid Cost | 55-Gal Free Delivery) - Buy in Bulk - DEF Exhaust Fluid | Pack Size | 55-Gallon Drum/Barrel | 275-330-Gallon Tote | FREE SHIPPING | Bulk Price | API Certified DEF diesel exhaust fluid is made from the purest ingredients, it works hard to purify your emissions and leads the field in environmentally friendly solutions for diesel vehicles.