This is all completely new to me (and probably most folks unless they're running around in brand new diesel vehicles). The last diesel car I owned was a 1998 (E

This is all completely new to me (and probably most folks unless they're running around in brand new diesel vehicles). The last diesel car I owned was a 1998 (Euro-2 standard when NOx emissions were more relaxed - so no DEF required [0]) Ford Mondeo which I disposed of in 2006 when the timing belt snapped ruining the engine. Since then I've owned older petrol engined high mileage "bangers" so I would never have encountered DEF unless I won the lottery and fancied a new Landrover :) [0]: https://en.wikipedia.org/wiki/European_emission_standards#Emission_standards_for_passenger_cars https://en.wikipedia.org/wiki/European_emission_standards#Em...