Brand of DEF for Duramax?

[AMA1295]

Buying DEF for my Duramax HC today for the first time, curious what brand everyone is using? I was just going to get the ACDelco brand, looks like you can get it on Amazon for like $12 a gallon...

 

[Holy Roller]

Please keep in mind that DEF doesn’t like sunlight and has an expiry date. Given that, the cheapest place will always be a farm supply or equipment dealer, like John Deere.

You can also buy it from a small pump or bowser at many truck stops.

But I’ve always bought from the dealer so that they can never play the DEF quality poor card on me.

 

[Bill 1960]

Walmart is usually around $7.xx for 2.5 gallons of their brand.

DEF is all the same, there’s no secret sauce that makes one brand differ from another.

 

[Stbentoak]

Walmart is usually around $7.xx for 2.5 gallons of their brand.

DEF is all the same, there’s no secret sauce that makes one brand differ from another.

Absolutely, Walmart has actually dropped it below seven dollars in our area. It’s the freshest and meets all specifications. No reason to pay more anywhere else. Used it for years in two or three different diesel vehicles...
Heat is the main enemy of DEF. In 70° or below it can last for 18 months, 2 years no problem.... but in continual 90° plus, it’s life can be shortened to as low as six months. It just slowly degrades....
The way I roll with DEF is I let it go down until the first reminder shows to refill it, then I just go and dump a 2.5 gallon container in, and wait for the next reminder. That keeps the whole tank pretty fresh and able to withstand any conditions and lets me motor quite a few thousand miles down the road before I hear from the indicator again....

 

[AMA1295]

Interesting.... my DEF gauge was reading 2.5 bars left which I translate to meaning I had at least 1/4 tank remaining, and it still took the full 2.5 gallons. Service manual says the tank is 2.5 gallons but by my calculations it must be at least 3.25.... good to know.