I was reading @AnywhereInTX 's review of the 2015 Ram EcoDiesel, which is really well done by the way, but I didn't know much about diesel exhaust fluid (DEF) which he mentions as his one complaint at the end of his review. Here is what he had to say about it:
I decided to do some research on both what DEF is and if there is something fishy going on with the Ram EcoDiesel's consumption of it.One thing that I am noticing is the rate at which this truck consumes DEF. Ram claims that the 11 gallon tank is designed to last 10,000 miles, that way the oil change and DEF fill can be done at the same time. However, I currently have 1600 miles on the truck and I am close to the 1/2 tank mark.
DEF is a fluid that is now required by the EPA. If a diesel vehicle runs out of DEF then the EPA mandates that the engine must disable. So its a pretty important part of your truck.
DEF reduces your engine downtime, maximizes fuel efficiency, and provides more O2 for efficient combustion. Through the use of DEF, nitrogen oxide emissions can be reduced to near 0. To sum that up, DEF reduces emissions and improves your engine's performance.
Ram says that the DEF tank should last for around 10,000 miles so that you can refill it at the same time as you change your oil. @AnywhereInTX says that his tank was at about a hlaf at just 1,600 miles, so something has got to give here.
There are two things I would bring up to solve this quandary. First, I am curious how accurate the gauge is for the DEF. Sometimes companies purposely make gauges less accurate so that people won't wait till the last minute, or until its too late, in order to do necessary maintenance. You could actually take a look inside the tank, if that's possible, to see if it actually looks like it is 1/2 full.
Second, towing and how you drive could affect the rate at which the DEF is consumed. @AnywhereInTexas was towing 6,000 lbs during his first jaunt in the Ram EcoDiesel. That extra weight could also be to blame.
All in all I think we have it pretty good though. The Silverado 2500 also uses DEF, but its tank is only supposed to last 5,000 miles between refills. So I think that the Ram 1500 EcoDiesel is doing pretty well for us when it comes to its DEF system.