Cow piss lol ad blue is a man made substance. And it is injected into the exhaust system to neutralise Nox particals that are harmful to humans when breathed in. Nox is produced when efficiently burning diesel. There is no real set amount to be used going by diesel mpg as there are too many factors. On a Daf it will not inject till a certian engine temp / temp before and after the cat / fuel being used percentage and throttle percentage has been met.
So on a cold winters day you may use none but in the hight of summer you may go through a tank a week. A truck running light will use hardly any but a heavy truck working hard will use a lot!
Last edited by ajamesc; 07-07-2014 at 11:58 PM.