RV Trip Planning Discussions

Go Back   iRV2 Forums > POWER TRAIN GARAGE FORUMS > Duramax Engine Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Thread Tools Search this Thread Display Modes
Old 08-06-2014, 03:47 PM   #1
Senior Member
gator67's Avatar
Join Date: Feb 2005
Location: everywhere
Posts: 523
Diesel Exhaust Fluid

What is the difference between the $2.79/gallon DEF at Pilot/Flying J and the the $12/gallon DEF (about $30 for a 2 1/2 gallon container) at a GM dealer?

Jerry & Shirley Friedman
2014 Chevy Silverado 3500HD
2015 Mobile Suites 38RSSB3
gator67 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 08-06-2014, 03:56 PM   #2
girlydogs's Avatar
Join Date: Jan 2014
Posts: 87
One says Gm on & the other one does not. Even the def that you buy packaged is the same stuff as bulk at the fuel pumps.


girlydogs is offline   Reply With Quote
Old 08-06-2014, 07:03 PM   #3
Senior Member
Join Date: May 2009
Location: Salisbury NC
Posts: 126
A higher markup.
pitcrew18 is offline   Reply With Quote
Old 08-06-2014, 07:17 PM   #4
Senior Member
macantic's Avatar
Join Date: Feb 2012
Location: Aiken,SC
Posts: 1,025
Do you really have to add that stuff to diesel fuel? will something happen to the engine if you don't?
Good Sam Life Members
Served in U.S.A.F.
macantic is offline   Reply With Quote
Old 08-06-2014, 07:29 PM   #5
Senior Member
Old Scout's Avatar
Join Date: Nov 2005
Posts: 5,693
Bottom line--you dont add it to fuel, its injected into the exhaust system....diesel engines built after 2009 wont run /will run derated unless DEF is present in the DEF tank...no DEF, not an option.
Old Scout
2003 Alpine 40' MDTS
New Braunfels, Texas
Old Scout is offline   Reply With Quote
Old 08-06-2014, 07:33 PM   #6
CFDfireman90's Avatar
Join Date: Aug 2014
Posts: 34
It's all the same, 32.5% urea and 67.5% water. Urea is essentially fertilizer.
CFDfireman90 is offline   Reply With Quote
Old 08-06-2014, 07:35 PM   #7
Senior Member
Join Date: Aug 2012
Posts: 587
Blue DEF at Walmart. 2.5 gallon for $12-15.00.
Automotive parts stores, will usually higher price!
And they are right, no DEF, no run!!
John and Susan. New 2018 Chevrolet 2500 2 WHD . 6.6 Duramax 3.73 rearend. .4 door ,Short, Bed W/Topper. 2017 Grand Design 297 RSTS. Our rescue dog Annie. Still ,Full timing since 07-01-2011. No sticks and bricks.
poppopc is offline   Reply With Quote
Old 08-07-2014, 11:01 AM   #8
Senior Member
Commercial Member
Join Date: Feb 2014
Location: Kent, WA
Posts: 127
All DEF that is labeled with "ISO22241" or "ISO22241-1" is manufactured according to the specifications for Diesel Exhaust Fluid and will perform the same in your Clean Diesel Vehicle. An API marking is also on most DEF that indicates the manufacturer has certified that the DEF meets ISO22241 specifications. Price varies greatly based on whether you purchase from an OEM (like GM) or from a bulk pump at a truck stop.
Erich Weinberg and Kathryn Whiting
Five Star DEF
Doctor DEF is offline   Reply With Quote
Old 08-07-2014, 04:19 PM   #9
Registered User
Join Date: Mar 2013
Posts: 1,919
Originally Posted by macantic View Post
Do you really have to add that stuff to diesel fuel? will something happen to the engine if you don't?
DEF is to never be added to the diesel fuel. It will cause major fuel system failure. As stated above if the vehicle is equipped with a DEF system, it must be added to the proper DEF. If it never gets refilled the truck will be derated all the way down to idle speed only.
jamesrxx951 is offline   Reply With Quote
Old 08-09-2014, 04:33 PM   #10
Senior Member
navychop's Avatar
Entegra Owners Club
Join Date: Jun 2012
Location: Lexington, TX
Posts: 479
And less than $11 for 2.5 gal at sams club
Rich USN-Ret & Cindy, Lexington TX
2015 Entegra Coach Anthem 42RBQ
2019 Jeep Grand Cherokee
navychop is offline   Reply With Quote
Old 08-09-2014, 05:12 PM   #11
Senior Member
lanerd's Avatar
Tiffin Owners Club
Join Date: Apr 2009
Location: Home in warm Sou Calif for the winter.
Posts: 1,401
It amazes me how many people think this is a fluid that is put into the diesel fuel. DEF = Diesel EXHAUST Fluid....not Diesel Fuel Fluid.

It really works. After almost 6000 miles, I can run my finger inside the exhaust outlet and my finger comes out perfectly clean....no sign of soot or any other discolorization (is that a real word?). Also, I get about the same mpg with this coach as I did with my previous non-DEF coach, so no big change there.

I typically get mine at Walmart ($11.97 for 2 1/2 gallons) and use about 1 gallon of DEF for every 800-900 miles (or 100 gallons of diesel fuel). I would like to get my DEF at the Pilot/FJ stations, but someone in their infinite wisdom designed and installed the tank on the passenger side of the coach and the station's pumps are on the driver's side. Good thinking!

Ron, Sandie and Lilly
2013 Tiffin Phaeton 42LH 400 ISL | 2011 GMC Terrain SLT-2
Roadmaster All Terrain | US Gear Unified Brake System | Pressure Pro
lanerd is offline   Reply With Quote
Old 08-10-2014, 01:42 PM   #12
Senior Member
Rburke8's Avatar
Excel Owners Club
Join Date: Jul 2012
Posts: 261
Please note that you should use the same brand all the time. Even though they say there is no difference between one brand or the other the fact is they are different. My good friend use whatever he could get when he needed it and the next thing that happen was the sensors reacted and the GM truck did not run for sh*t. I always use Blue def and nothing else. Also the def has a shelve life. Buy it when you need it. Just plan appropriately. There was quite the discussion either here or the Excel forum about def that an engineer that works with the stuff wrote up some good info concerning def.
Rburke8 is offline   Reply With Quote
Old 08-10-2014, 01:54 PM   #13
Senior Member
Join Date: Feb 2014
Location: Bamber Lake
Posts: 445
I don't use the stuff my coach is a 2003 but look out when your buying the stuff Wallmart had a problem with people returning the container with water in it for credit, thats a form of shoplifting. The associates don't check it and its returned to the shelf for sale. No matter where you get it make sure the seal isn't broken.
RayJr is offline   Reply With Quote
Old 08-10-2014, 02:17 PM   #14
Senior Member
tcopeland's Avatar
Thor Owners Club
Freightliner Owners Club
Carolina Campers
Join Date: Feb 2011
Location: Jacksonville, NC
Posts: 1,322
Mine is on the passenger side also.
I carry a 5 gallon jug to fill at the truck stops then put it in the DEF tank at the next layover. Sure beats that $12-2 1/2 gallon $$$'s.

2016 THOR Tuscany XTE 36MQ
2011 Jeep Wrangler Unlimited
tcopeland is offline   Reply With Quote

diesel, fluid

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Allison not hot enough to check fluid level? Vanwill Monaco Owner's Forum 33 10-11-2016 07:21 PM
ATF fluid service on E40D/4R100 questions chucksel Ford Motorhome Chassis Forum 40 10-23-2015 09:12 AM
Looking for diesel fuel jillie Class B Motorhome Discussions 14 05-16-2014 07:55 AM
How to Drive a Diesel MH for Dummies? reubenray Class A Motorhome Discussions 6 03-25-2014 08:34 AM
Allison md3060 fluid never changed in 107k hbrown Allison Transmission Forum 41 05-06-2013 03:24 PM

» Featured Campgrounds

Reviews provided by

All times are GMT -6. The time now is 05:30 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.