Starting in 2010 diesel engines have to meet stringent emission requirements.  Most diesel engine manufacturers have chosen a technology called Selective Catalytic Reduction (SCR) to meet these requirements. 

If you purchase a car, truck, tractor or any diesel powered product with SCR technology, you will need DEF.

Diesel Exhaust Fluid (DEF) is a very pure solution of urea which meets the automotive industry specification defined by ISO 22241.  It is a clear liquid similar in appearance to water.

DEF is safe to handle and use; it is not explosive, flammable, toxic, or subject to any hazardous product regulations.  It has a shelf life of 18 months if stored properly.