The heck is DEF?

A popular beverage from California.

Also used to remove the extra soot produced by the EGR system.

 

Diesel Exhaust Fluid. The catalyst for a Selective Catalytic Reaction that converts the 'bad' stuff in diesel exhaust into 'better' stuff for the environment. The fluid itself is basically horse pee.

 

........according to WikiPedia. And the urea can be found as the active ingredient of many types of modern soaps, and it fulfills the same basic function in the converter as soap does to grease on your hands. Except in the converter it deals with soot instead of grease, if that makes any sense........

And the connection with horse pee is real. It is rumored that some DEF are manufactured from urine off dairy farms, filtered, and spec'd to requirements. I would not sell that as the truth though.

If you are into the nitty gritty, see: http://www.cumminsfiltration.com/pdfs/product_lit/americas_brochures/MB10033.pdf

 

DEF is a expensive additive designed to make u spend more money.

 

Def... Lepperd? A great 80's band!

The title says it all but "What".

 

Not totally, by using DEF the engine makers are able to lower the amount of EGR used. In theory, you should get better fuel mileage thus off setting the cost of the DEF.

 

Is the Diesel Particulate Filter used used with DEF? I've seen trucks with the the little tank with the blue cap. How many miles do you get to a gallon of DEF, and what would happen if it were allowed to run out?