DEF

[geekything]

I just bought a 2018 ecoDiesel. This is the first diesel vehicle I've had, and DEF is definitely new to me.

Is there a rule of thumb on the ecoDiesel about how much DEF I'll use? I think it's something like 2% DEF versus volume of fuel? How big is the DEF tank?

I've also read on some cars with diesel, people get their DEF tank filled when getting an oil change. Is that really practical on a RAM?

 

[Scottly]

More important is the **quality** of the DEF you use. If you use DEF that doesn't meet specific gravity measurements and you set off the on-board system warning, your tank will need to be drained and the system blead...and THAT is not covered under your warranty.

Me personally, I pay a bit extra and buy my DEF at the dealer near my house, so if it ***** up, they own it. Otherwise, I'd use BlueDEF and make sure it's a recent production date.

 

[KSH]

I believe the def in my eco lasted between 8 and 10k miles. That's mostly highway and towing. I always filled it up at truck stops. Depending on where you go you might need a magnet.

https://www.amazon.com/Five-Star-DEF-Magnevator-Activating/dp/B01BLS220A

 

[JohnnyMac]

I too have an 18 Eco that’s my first oil burner. I’m at about 1300 miles and my def gauge is still pegged on full. When it comes time to fill it up, I’ll probably go with BlueDEF. Costco sells it pretty cheap.

 

[Statcher1]

Just make sure you buy your DEF from somewhere that has a high turnover rate. And don’t top off the Def tank. Run it down till the full light come on and add a couple gallons. Or you will get a engine light or incorrect def message to pop up. Atleast that’s what happens to me with my Cummins.


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[mtnrider]

I'm not sure how much DEF your Eco will consume? On my 6.7 I just add it when the gauge gets close to empty (or the light comes on). I never add it until I am close to empty so I am using up the older stuff in the tank first. I've never tracked miles between adding but it's quite a few (add 2.5 gallons once every 2-3 months or so?) and I put around 16K on my truck a year

DEF is DEF, it's all made to the same specs (and only by a few manufacturers) and re-branded for everyone.
I've been using cheap Wal Mart DEF since day 1 and have had no issues. I just check the dates to make sure it's fairly recent (and it always is) and that the seal is good. Internet rumors circulate saying be careful that people buy it and return it with water in it. I've never seen or heard of an actual case so I think it was one of those one off things that has just spread out of control on the interweb.

Some swear by truck stop DEF and if you have one near you and it's convenient that may be easy for you as well.
And of course there's the peace of mind of buying it at the dealer (more expensive) but "if" you ever had an issue with it you can probably point the finger back at them. Pretty unlikely scenario but if it helps you sleep at night it might be worth it.

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[mtnrider]

I too have an 18 Eco that’s my first oil burner. I’m at about 1300 miles and my def gauge is still pegged on full.

If it's anything like the cummins gauge it's not very linear. It will stay on full for a long time before it moves then it will go more quickly on the last half.

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[geekything]

If it's anything like the cummins gauge it's not very linear. It will stay on full for a long time before it moves then it will go more quickly on the last half.

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Hah! So it's built just like the gas gauge

 

[geekything]

Lots of great feedback, guys. I don't know if buying from the dealer is really an insurance policy (they'll just accuse me of having used a third party DEF at some point!). I do have a truck stop very close to me, so I might check that out -- it makes sense the big rigs need to fill up on good quality DEF all the time!

 

[SyN]

If you buy your DEF in a jug or box it will have a code.
You can read the code to tell the production date.

You want to buy the newest product.

If you fill from the pump - well cross your fingers!
It should be decently fresh if it's from a very busy truck stop!



Here is a cheat sheet I made! You
It's not perfect but it will get you the newest production from the shelf.

I keep the pic in my phone - so when I go to buy I just bring up the pic & read the codes on the Peak box!

The cooler the environment the DEF is stored the longer it will keep!

 

[mtnrider]

The Wal Mart DEF actually has a real date on it so easy too read. Blu DEF you have to use a cheat sheet. Not sure about any other brands?

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[JohnnyMac]

Hah! So it's built just like the gas gauge

My Nissan Titan got about 175 miles on the first half of the tank and 60 on the second. Crazy.

 

[KSH]

I too have an 18 Eco that’s my first oil burner. I’m at about 1300 miles and my def gauge is still pegged on full. When it comes time to fill it up, I’ll probably go with BlueDEF. Costco sells it pretty cheap.

The def gauge doesn't start measuring until it's about 1/4 empty. There's a you tube video you can google.

 

[crash68]

Is there a rule of thumb on the ecoDiesel about how much DEF I'll use? I think it's something like 2% DEF versus volume of fuel? How big is the DEF tank?

1- 2% is about right when driving, in terms of mpg it's upwards of 1100 miles per gallons of DEF, so it is possible to fill the DEF tank one an oil change. If you tow you'll consume a bit more def. The tank holds 8 gallons.
As others have stated DEF is DEF it's all the same or it won't meet the purity standard(ISO-22241-1). Usually your best bet for DEF is to fill up at a truck stop pump for freshness and price.
Keep in mind DEF freezes at about 12°F so if you live where it gets that cold, don't try to fill the tank to the very top when it's going to be cold.

 

[geekything]

As others have stated DEF is DEF it's all the same or it won't meet the purity standard(ISO-22241-1). Usually your best bet for DEF is to fill up at a truck stop pump for freshness and price.
Keep in mind DEF freezes at about 12°F so if you live where it gets that cold, don't try to fill the tank to the very top when it's going to be cold.

Because it'll burst the tank?

 

[crash68]

Because it'll burst the tank?

probably best not to test burst strength of the tank.
I'll fill mine to the top in September and the tank level just drops off full about the time the freezing weather hits.

 

[Brane]

I have a concern on my 2014 Big Horn because the DEF gauge hasn’t moved in 1500 miles. I saw the eco diesel post about it going 1100 miles per gallon of DEF. Does anyone know if this holds true for the 6.7 Cummins?

 

[mtnrider]

I have a concern on my 2014 Big Horn because the DEF gauge hasn’t moved in 1500 miles. I saw the eco diesel post about it going 1100 miles per gallon of DEF. Does anyone know if this holds true for the 6.7 Cummins?

Don't worry about it, the gauge is not linear. It will sit on full for a long time then start to move.


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[Brane]

Don't worry about it, the gauge is not linear. It will sit on full for a long time then start to move.


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Thanks mtnrider

 

[WY-Dave]

The first DEF I put in was BlueDef, then the WallyWorld version after that. 16k miles and no issues (knocking on wood). The tank is supposed to hold 5.5 gal. When it hits 1/2, that is when I fill. Around here Wally World has a high turn over rate and I have seen nothing older than 2 months. Usage varies, hot rodding, towing, temp etc. When it hits 3/4 is when I buy a new jug. None of the truck stops here have it at the pump.