As of 2010, the US Environmental Protection Agency requires that diesel emissions contain a 97 percent reduction in their sulfur content. Not just trucks and automobiles are affected by this rule. Locomotives, ships, and stationary power plants are required to conform to the same standards.
Selective Catalytic Reduction (SCR) is the leading technology being used to meet 2010 emission regulations. SCR technology uses diesel exhaust fluid (DEF) as a catalytic converter to reduce NOx emissions. DEF is a clear non-hazardous liquid. DEF is NOT a fuel additive, is stored in a separate tank, and never comes into contact with diesel.
Diesel exhaust fluid (DEF) is a specific combination of the chemical urea (32.5%) and de-ionized water (67.5%) used in the application of transportation, that together acts to convert harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor using selective catalytic reduction (SCR).
Diesel Exhaust Fluid is produced to the international standard ISO22241. Any contamination will affect the quality of DEF, and this may cause your catalyst to need expensive repairs. Use dedicated Diesel Exhaust Fluid tanks and dispensing equipment.