DIY diesel exhaust fluid

I passed by a Brewer fleet fueling station today. A sign advertised ‘diesel exhaust fluid’. I wondered if this is something truckers put in their drinks, a kind of bitters. I looked it up when I got home and wondered why you can’t make it yourself.

I think they are talking about that blue def that has to be added now for emissions. Separate tank that needs to be filled up same as fuel and evidently is injected into the engine combustion chamber like fuel. I’d never heard of it before a year or so ago but now see it everywhere.

Diesel exhaust fluid is basically extremely overpriced urine.

Blue Def is required in diesel engines so the secondary catalyst can reduce the emissions of Nox.


It is urea based, but urea is NOT urine.


Urea is a component of urine. I haven’t looked it up, but I suspect the separation isn’t hard - for a chemist. If it only comes in contact with exhaust one can’t hurt the engine by using the wrong stuff - though it could stink. Urea is the solid with the highest concentration of nitrogen, making it the cheapest fertilizer. It’s for sale on eBay.

I use a urea cream to treat calluses.