Diesel Exhaust Fluid

[gator67]

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?

[girlydogs]

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.

Ben

[pitcrew18]

A higher markup.

[macantic]

Do you really have to add that stuff to diesel fuel? will something happen to the engine if you don't?

[Old Scout]

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.

[CFDfireman90]

It's all the same, 32.5% urea and 67.5% water. Urea is essentially fertilizer.

[poppopc]

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!!

[Doctor DEF]

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.

[jamesrxx951]

Originally Posted by macantic

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.

[navychop]

And less than $11 for 2.5 gal at sams club

[lanerd]

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

[Rburke8]

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.

[RayJr]

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.

[tcopeland]

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.