Hey guys, I finally have some information on mileage for my DEF fluid! But... I don't like it. When I bought the truck it came with a "full tank" well, the meter was on full anyway. sense then I have drive just shy of 10,000 miles of which over 4,100 where with a trailer, you know the one.
When I filled up my DEF tank to... overflowing... last week it was the 3rd time I've added fluid but the first time I had completely filled it, so up until now I haven't been able to give a full report.
The first time put some fluid in was in Kellogg ID when I had an oil change at exactly 2000 miles. I was just over half a tank if memory serves. They put in 2 gallons which didn't fill it all the way but I hoped I'd have enough to last till me 10,000 mile service.
A few weeks after I got home from my long trip I ended up getting fairly low on DEF fluid yet again and bought 5 gallons, thinking I've got an 8 gallon tank, this should top me off! Alas, I was wrong. (Odometer read 5168 when I added those 5 gallons.
Last week, I was in Anchorage yet again and noticed that I was in the red zone, not knowing when Id be close to a store again that sold DEF I went ahead and picked up 7.5 gallons and added what Id estimate to be about 6.5 gallons. My Odometer read 9,556.
So that means as of right now I've gone through about 21.5 gallons of DEF fluid in under 10,000 miles.
WHAT THE HELL HAPPENED TO 8 GALLONS FOR EVERY SERVICE?!?!
(Servicing being every 10,000 miles) At the rate RAM mentioned I should be getting about 1,250 miles per gallon of DEF. but as it sits I'm getting about 444 miles per gallon.
I understand that the higher my RPM, the more fuel I use,thus the more DEF fluid required. So when I pulled that trailer I expected to see reduced longevity in my DEF tank. But even if we take the calculation of say... 6 gallons in 4,388 miles that still means I averaged 731 miles per gallon of DEF. (I took those figures from the second and last time I filled my truck with DEF)
Now I've gone about 350 miles from when I had literately overfilled my DEF tank and I can see that the DEF gauge in the dash is actually off "Full"and almost halfway between the next bar. Somethings got to be wrong or some ones lying to us (me)
In conclusion I am not happy with the amount of DEF Fluid I consume. Hopefully it'll be near my 20,000 mile service before I have to bring it up again, but with these numbers mentioned above I guesstimate it'll be closer to 15,000 miles. and to answer your question, No, I do not let my truck sit and Idle. The only other thing I can think of is the Quality of the DEF Fluid I've been buying being below the correct rate. In response to that I've now purchased from 3 different locations and the truck is supposed to be smart enough to know if the urea to water level is to low.
