DEF (Diesel Emission Fluid) Pro's or Con's

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Wi1dBill

Wi1dBill

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Jun 20, 2013
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Looking to upgrade our truck and not too sure if I want a new diesel because of the DEF and some of the things I'm hearing and reading about.. 
Any experience would be appreciated.


WildBill
 
I had a 2012 Dodge Ram 2500 Mega Cab which was the last year before DEF.  Never had any issues other than really poor fuel economy when it was going through a "cleaning" cycle which were short periods.  Replaced it with a 2017 Ford Super Duty F250 this year which of course requires the DEF.  I uses very little DEF under most types of use and only when really towing a heavy load do I notice going through the DEF.  performance is excellent and you can tell it runs even cleaner than my old Dodge which I alway thought ran clean.  Barely can smell any diesel at all when it runs even while hooking up a trailer and back behind it.  I have just ove 17,000 miles and added 1 box of DEF since I purchased it and it has a half tank of DEF left.  About 80% of my miles were towing either our enclosed 3 place snowmobile trailer or enclosed 5 place motorcycle trailer so again DEF usage is pretty minimal.  I think your biggest concern with a newer or older truck would be if you intend to do any engine modifications.  My 2012 Dodge Ram was a "unique" year for emission controls and there are very few tuning options you can do on that year engine without completely changing everything.  No simple plug in tuners etc. 
 
If you want a new diesel you will need it.
I've had trucks that use it for 7 years and haven't had any problems.
It doesn't just stop when you run out like I read on the internet.
The message center in my truck warns for several hundred miles that it's going to run out. It's readily available at truck stops and walmart/sams and other stores. 
 
DEF is a none issue.  Yes, you need to add it from time to time.  I never wanted a diesel when they were slow, noisy, stinky and smokey, I like the current much better.
 
Another DEF user. Almost 60,000 miles and no problems. We keep a spare box of DEF in the truck and fill up the DEF tank when the truck tells us it is half full. I am another one who would not have bought an older diesel due to pollution concerns. Love this truck though.
 
The "slow, noisy, stinky" had much more to do with the pre-turbo days than DEF, but I agree heartily!

DEF is used in the NOx emission reduction process and is not in any way a performance enhancer.
 
We are on our first ever diesel and the DEF is pretty much a nonfactor. We add it as needed and just continue on.
As mentioned above, it's readily available nearly anywhere. Even places like Home Depot carry it.
We did just have a problem with the DEF indication in our 2016 GMC 2500HD Sierra. The "so many miles" to empty came on and it goes to a percentage remaining indication. That's always been the case and when I'll add more DEF. It usually comes on around 25% to go to empty. Anyway, this time it got to 24% left and I got some added, 2.5 gallons, and the 24% would not clear. Even after a week of driving. Took it to our GMC dealer and the tech was able to reset it with the scanner tool they use to scan for errors. Anyway, as far as using DEF, no biggie.
 
DEF is a non-issue for me.  Like you I had my concerns when purchasing my diesel truck, but those concerns went away with actual use.  My truck performs just fine, adding DEF is not only easily obtainable but easy to add and in my experience I have had to add it so infrequently it certainly has not been an excessive cost of operation.
 
Gary RV_Wizard said:
The "slow, noisy, stinky" had much more to do with the pre-turbo days than DEF, but I agree heartily!

DEF is used in the NOx emission reduction process and is not in any way a performance enhancer.
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Actually it is in a way a performance enhancer.  With the DEF use, the engine can be designed and tuned for the performance the engineers want and still meet the NOx emission requirements.

http://news.pickuptrucks.com/2014/04/top-10-facts-about-diesel-exhaust-fluid.html
 
Anyone have an opinion on fuel consumption on older units compared to the new def units. I have heard truckers complain how much more fuel they burn now compared to the older trucks.
 
muskoka guy said:
Anyone have an opinion on fuel consumption on older units compared to the new def units. I have heard truckers complain how much more fuel they burn now compared to the older trucks.
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I've got a 2500 Silverado and on level ground, I get 21/22 MPG
 
Rene T said:
I've got a 2500 Silverado and on level ground, I get 21/22 MPG
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Our 2016 2500HD 4x4 GMC gets similar mileage. Around 12 mpg when towing.
 
muskoka guy said:
Anyone have an opinion on fuel consumption on older units compared to the new def units. I have heard truckers complain how much more fuel they burn now compared to the older trucks.
Click to expand...
It's not due to the SCR (component that uses DEF) The lower mileage is due to Ultra Low Sulfur Diesel which caused poor fuel economy in the older trucks. The newer ones (2007 or newer) are optimized for the fuel.
 
Anyone have an opinion on fuel consumption on older units compared to the new def units. I have heard truckers complain how much more fuel they burn now compared to the older trucks.
Click to expand...

Lot's of opinions float around the net, mostly short on facts. Diesel emissions regulations did cause a drop in fuel economy, including some tuning effects as engine combustion design changes were introduced and then slowly improved. There were major changes in 2007 and again in 2010.  ULSD itself doesn't effect combustion, but the reduced sulfur content adds to engine lubrication concerns. The DEF is part of an emissions control method called Selective Catalytic Reduction (SCR), and SCR allows diesels to meet the EPA standards without impacting fuel economy. That was an improvement over previous emission technology, so in that sense SCR & DEF enhanced previous performance. However, it only brought back the fuel economy lost circa 2007.

Many RVers with older, mechanical control diesel engines claim much higher fuel economy than newer engines. The reasons are complex and include the implicit effects of larger & heavier coaches and higher horsepower engines as well as technology changes. Explaining it all is far more than we can deal with here, but you can finds much more info if you Google 'diesel emissions', 'diesel SCR', 'diesel fuel economy', and similar terms.
 
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