>17754107
DEF is not added to your fuel, and no you can't run newer diesels that require it unless you "delete" it which is illegal in many places and requires reprogramming the ECU. Without deleting the computer will cut power and limit you to about 5mph when you run out of DEF.
"Diesel Exhaust Fluid (DEF) is a solution of urea and water that's injected into the exhaust stream of diesel vehicles to turn NOx gases (harmful emissions) into nitrogen and water. This system is called a Selective Catalytic Reduction (SCR) implemented by vehicle manufacturers to meet EPA emissions standards in 2010"