Diesel exhaust fluid (DEF) - Montana Owners Club

MIMF · 03-05-2014, 02:21 AM

For any of you folks who have the newer diesels that use the DEF, what is the typical usage you have experienced? When I took delivery last week, the guys at the dealer, especially the Service Manager, is saying that the tank holds 5.3 gallons. He states that I should not have to refill between the normal service intervals. They refill the tank at the service and that unless I have the truck setting and doing a lot of idling, I will use 1 gallon for every 1000 miles. I have no reason to disbelieve what he stated but, just wanted to touch base with you experienced gents.

Also, I have noticed that when the truck is running and I walk around the back end, I smell something similar to burning paper. Especially if I have just driven it. That is way more pleasant than the exhaust fumes from the old truck. Probably a mind thing, again but, I swear the exhaust from the old truck for some reason, would remind me of jet plane exhaust at airports. Now, I look around to see what's burning!!

timandsusan · 03-05-2014, 02:56 AM

My two year experience with DEF fills is as follows--not really scientific but I did experience it!
NOT TOWING--about 1000 miles per gallon of DEF
TOWING-in the West--up and down passes etc. About 600 to 700 miles per gallon. I drive about 60 to 65 mph when towing. I have towed about 5000 to 6000 miles so far. The truck works great--but I tend to not sniff the exhaust!

capn chris · 03-05-2014, 02:58 AM

Dale,
On my Ford, I typically have the oil changed every 5k miles and DEF is topped off at that time. Seems to use more when towing, but I have still made it to the 5k mark. Just be sure they fill it and not just add one jug (2.5 gal.)!

JandC · 03-05-2014, 03:01 AM

I just turned over 34,000 miles and my DEF usage is about 1,000 miles a gallon when not towing and less when towing. My truck doesn't have an actual DEF gauge but I usually add a couple gallons between oil changes and I change my oil every 7,000 miles.

DonandBonnie · 03-05-2014, 03:27 AM

Waiting for an empty DEF tank has always proved inconvenient for us. Even though our Ford specs say that the tank should hold 5 gals., we have never been able to add two full jugs without overflowing. Although availability is improving, there are still many areas where it is difficult to find. To get around this, we watch the fluid level meter and when it indicates that the tank is half full, we add one 2-1/2 gallon jug.

BB_TX · 03-05-2014, 03:28 AM

My usage pretty much follows the previous posts. Although I do not have a DEF gauge, on the information center I can look at the DEF status. It will say OK if over half full. And "Less than half" (or something similar) if it drops below that. I check it occasionally and if it is less than half I just drop by the auto parts store and buy a 2 1/2 gal jug. That will take it right back to or near full.

jfaberna · 03-05-2014, 04:05 AM

on my 2014 Ram 3500, I heard a lot of the same crap as the rest of you. However, my DEF tank holds 8 gallons and I have a gauge on the dash. It was full when I picked up the truck and I now have 5300 miles on it. So if it's 1000 miles/gallon why have I added 3 2.5 gallon boxes of DEF??? I've only towed the 5W for 3000 of that total miles. It maybe right but I don't know. Everything works great, but when I had the first service/oil change today, they did update the engine software when included something related to the DEF system.

jfaberna · 03-05-2014, 04:11 AM

I went back did the math and maybe I'm getting 500 miles/gal when towing and 1000 when not. Based on what I said above, that may be right. My manual says when the DEF gauge is at 1/2, I can safely add a box of DEF. That's what I've done.

MIMF · 03-05-2014, 07:01 AM

I did ask the question at the dealer if it would use more when she is working harder towing the 5er. They indicated it would some but, should still get me thru the service interval. I'm not sure he knows for sure. Any way, my truck does not have a guage, either. The manual says the DIC will warn me when it gets down to 1000 worth left in the tank. So, I am tempted to get a gallon to keep in the truck for just incase! Especially if have the 5er hooked up. I know the DIC works because, an warning came on the other day as we were going down the road that said, "Back-up Assist is Blocked". Got the book out and learned it had to do with a rear bumper sensor covered with snow! I was able to reset it with no issue. Gotta' figure out how to get a picture of this machine posted on here.

RKassl · 03-05-2014, 07:04 AM

On my 2011 Silverado, the more diesel you burn the more DEF is consumed, towing the Monty causes us almost double the DEF as compared to normal driving without the load.

busterwms · 03-05-2014, 08:03 AM

Our 2011 Silverado DEF alerted us that our Exhaust Fluid is of poor quality and the engine light came on. We took it to our local Chev Dealer and they had to reprogram the computer thingy. the poor quality sign went away but yesterday when we were again towing the Monty the stupid lite came on again. Guess it will be another visit to the Dealer. No one else wants to mess with the DEF stuff.

Artemus Gordon · 03-05-2014, 09:16 AM

I have added DEF at about 4000 - 5000 miles in tow mode. Truck gives me plenty of pre-warning to add it !

DonandBonnie · 03-05-2014, 11:04 AM

Is there anything corrosive about this stuff? When we overflowed the tank, the DEF that we didn't get cleaned up dried as a white chalky substance. Didn't want to risk spilling it again.

Sheepdog · 03-05-2014, 11:24 AM

DEF is 1/3 pig urine and 2/3 water. The urine contains the nitrogen (ammonia) that is used in the reaction to reduce nitrous oxide emissions. The urine could stain the paint and should be washed off if spilled.

PackerFan · 03-05-2014, 11:28 AM

Wonder if you drink a lot of Beer you could fill the tank yourself!!

CRUZIN 2 · 03-05-2014, 12:19 PM

RKassl

On my 2011 Silverado, the more diesel you burn the more DEF is consumed, towing the Monty causes us almost double the DEF as compared to normal driving without the load.

*Referring to the post above~
We had the exact same problem with our 2011 GMC 3500 and had it into different Dealerships, with no results after 2 plus years! We finally, after calling customer service in Detroit, explained our problem and they lined us up with a dealership that was determined to find the problem! The results were low pump pressure on the DEF fluid which in turn gives you false codes on the problem. They put in a new DEF pump and tank a year ago, and the problem was solved. The truck runs really good now. Hope this will be of some help to you.

BB_TX · 03-05-2014, 01:19 PM

Urine contains urea but DEF does not contain urine. DEF contains a very high purity automotive grade urea. Urine contains a very low percentage urea mixed in with other bodily waste.. So don't try peeing in your DEF tank unless you want your engine to shut down.
Google it and read all about it.

Bigsky3625RE · 03-05-2014, 01:19 PM

Our usage is similar. Once the 1000 miles left indicator comes on the DIC will start rreading in % left.

That is the point I add 2 1/2 gallons. I will top it off while listening to the trickle in to the tank. When you hear the trickle stop, time to stop filling.

And yes, clean up spills. It will damage paint.

MIMF · 03-06-2014, 01:17 AM

Thanks everyone, for the great information here. I think I will get a spare bottle and keep it handy when we are pullin'. That way, if the warning comes on, at the next fuel stop, I'll dump a gallon or 2 in.

mhs4771 · 03-06-2014, 03:06 AM

Dale, just an FYI, but you can also get DEF at most Pilot/Flying J's in the truck lanes. Have never tried it, but been thinking of saving one of the 2 1/2 Gal containers and refilling as their price was running less the $3.00 per gal last I checked. Making it an even better deal than Wally World.

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