Gumout® PRO DEF
Diesel Exhaust Fluid

Gumout® PRO DEF diesel exhaust fluid is the easiest and fastest filling DEF product available. The unique spout and hose system combined with our fast-fill box package eliminates the frustration of filling your DEF tank.

No lifting or pouring needed. Simply set the 2.5 gallon box on your vehicle, insert the hose in your DEF tank and open the spout for a quick and easy DEF fill.

It’s easy and reliable. PRO DEF meets all OEM standards and is backed by a quality brand you can trust.   

Diesel Exhaust Fluid (DEF) is an emissions reducing treatment for diesel engines. DEF meets AUS32 and ISO 22241 standards for diesel engines equipped with the new Selective Catalytic Reduction system. DEF is NOT a fuel additive.

  • Fast fill
  • Spill-free
  • Reaches any DEF tank location
  • No lifting or pouring
  • Meets all OEM standards
  • API certified

Frequently Asked Questions on PRO DEF


The spill-free, easy-flow spout makes filling your tank fast and simple.
The unique, 3 foot flex hose will reach any DEF tank location simply and easily.
PRO DEF’s fast flow box package sits on any flat vehicle surface for a hands free fill.

Note: Use only per label directions.


  1. Push in tab
  2. Tear at perforation and remove section
  3. Remove perforated section from package
  4. Take hose out completely
  5. Raise the tab assembly
  6. Affix the hose by sliding onto the tap until it clicks into place
  7. Place hose in the DEF tank in your vehicle
  8. Open the tap to dispense DEF
  9. Do not overfill DEF tank.


  • DO NOT mix with diesel fuel.
  • DO NOT overfill DEF tank. When fluid reaches top of fill pipe, stop filling.
  • DO NOT top off. Store between 230 F (-5C) and 680 F (20C).
  • Protect against direct sunlight. Avoid contamination while filling. If spilled on painted surface or under hood, wipe immediately with a damp cloth.
  • DO NOT mix with any other substance.
  • Use and store only as directed.
  • ISO 22241 / AUS 32

STORAGE: To store left-over fluid, clean the tube to remove any soil then return it to the box to avoid system contamination during future use.

GUMOUT®  Professional - Diesel Exhaust Fluid
* available at select retailers.
See How Easy PRO DEF is to Use.
Diesel Fuel Treatment
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