I just picked up a new Dodge 2500 diesel and the fun new thing the EPA has forced the builders to add is the Diesel Exhaust Fluid system.(DEF). A 5 gallon ish resivor that holds this extremely toxic fluid that is injected into an exhaust chamber to capture the particles exhausted and trap them. Then at some preprogrammed point the waste is recycled though the engin to burn off. This new class of diesel engins is also in the new farm and construction machinery. The newer John Deer's have a second exhaust port for the burn off, that exhaust can put out up to 500 degrees during burn off!
You are a little mixed up. The solution is not toxic. It is deionized water and urea. Urea you piss out every time you pee. It stinks, but is non toxic. This is "after treatment" to turn nitrous oxide into nitrogen and water.
The burn off is to regenerate the DPF, which is the Diesel particulate matter filter. This requires the temperature to be raised in the exhaust. This requires excess fuel to be added, starving the engine of air and retarding the timing. All this ruins the engine and gives it a very short life. Some systems only inject the excess diesel with pistons at top dead center this is better. Even better to inject diesel with a separate injector into the exhaust for burn off. This is probably the best and is now on Duramax trucks.
These exhaust systems need replacing periodically and the cost is $7000 a pop, so start saving.
In addition read your manual as to when the DPF filter needs service, on some models it can cost as much as $2000. Service is usually around the 90,000 to 100,000 miles. If you use your vehicle for short trips the service point will come much sooner. You need to reach highway speed for about 7 miles everyday you use the truck.
All this has turned the workhorse diesel engine a nightmare. Oh, and if you live anywhere near here where it gets very cold, expect to buy lots of new engines, as in cold weather the excess fuel injection does not work well and results in hydraulic lock of the pistons and destroyed engines.
And one more thing, diesels used to be much more resistant to catching fire. Because of all this they catch fire not infrequently now it seems, especially our school buses up here on Minnesota.
Good luck with your new truck!