Diesel exhaust fluid

Blue Sky DEF is made and distributed for retail sale by Prime Lubes, Inc.[6] Diesel engines are typically operated with a lean burn air-to-fuel ratio (over-stoichiometric ratio) to ensure the full combustion of soot and to prevent them from exhausting unburnt fuel.

[8] In 2007, the United States Environmental Protection Agency (EPA) enacted requirements to significantly reduce harmful exhaust emissions.

[10] The injection rate of DEF into the exhaust depends on the specific after-treatment system, but is typically 2–6% of diesel consumption volume.

This low dosing rate ensures long fluid refill intervals and minimizes the tank's size and intrusion into vehicle packaging space.

[16][17] For the SCR exhaust cleaning system to function at low temperatures, a sufficient amount of the frozen DEF must be melted in as short time as possible, preferably in the order of minutes.

[18][19] In Europe, Regulation (EC) No 692/2008[20] specified in Annex XVI point 10 that DEF from a frozen tank at a core temperature of −15 °C (5 °F) must become available within 20 minutes when starting the engine at −15 °C (5 °F).

[23] Vehicles' selective catalytic reduction (SCR) systems and DEF dispensers are designed in a manner that there is no corrosive impact of urea on them.

Bulk volumes of DEF are compatible for storage within polyethylene containers (HDPE, XLPE), fiberglass reinforced plastic (FRP), and steel tanks.

In Europe, increasing numbers of fuel stations offer dispensers that pump Diesel Exhaust Fluid rather than the traditional method of using disposable, single-use plastic containers.

These pumped dispensers are often targeted at commercial vehicles but are now also starting to emerge as a solution for the growing number of passenger cars that require DEF by volume.

At airports, where DEF can sometimes be required for diesel ground service vehicles, its labelling and storage must be carefully managed to avoid accidentally servicing jet aircraft with DEF instead of fuel system icing inhibitor, a mistake that has been blamed for multiple in-flight engine failure and grounding incidents.

In 2015, South Korea had made it mandatory for diesel cars to use urea solutions to control emissions, a move that now impacts 40% of registered vehicles.

[28] The South Korean government started rationing urea solution, and banned its resale as panic buying by drivers exacerbated an acute shortage that could cause transport and industry to grind to a halt.