Additives for diesel engines allow many diesel vehicles to keep pace with ever stricter emissions legislation, while also providing improved Diesel Particulate Filter (DPF) performance. Typically, diesel additives will either be Fuel Borne Catalysts (FBC) or Diesel Exhaust Fluid (DEF); which offer differing benefits for processing the noxious gases produced by the diesel combustion process. However, the market is also flooded with fluids that make unsubstantiated claims about improving performance, so how diligently should the consumer treat these fluids?