What DEF Fluid?

[JayceeP]

Anyone have any suggestions on the “best” DEF to use? I read the manual… doesn’t say much aside from meeting the noted standards. Get it from the dealer or any automotive store?

This is my first diesel (2024 Yukon XL SLT) and DEF level is at 50% after 3,000km (2,000mi). Seems a bit heavy on the consumption but assuming that’s just break-in consumption and definitely some shorter trips in the mix.

Thanks!

 

[Stbentoak]

Wal Mart Super tech DEF..... End of story.....

 

[martinajm]

Truck stop DEF from the pump... End of Story....

 

[UsualSuspect]

Truck stop DEF from the pump. The stuff has a shelf life. Rule of thumb I operate on, never let it go below 1/2 a tank. My mechanic told me years ago to always stay above a 1/2, if you get bad DEF, it will be diluted enough with the good that is there and you should be ok, and worse case you will make it to a dealer. We have had a few tow in's from bad DEF, doesn't happen often, and all of them said they fill it when it's empty.

 

[StephenPT]

I prefer the Walmart DEF because each bottle has a date on it. I can usually get a jug that is less than a month old. I watch my Bank IDash and when I get below 50% I add another jug.

 

[JayceeP]

I bought a 2.5 gallon jug of Motomaster Blue DEF from Canadian Tire. My gauge said it was at 50% and it took the whole jug which would be half the def tanks capacity. The gauge now reads full. I know it’s not a perfectly accurate reading but good to see it’s in sync. On the flip side, seems like a lot of DEF consumption over 3200km/2,000miles.

 

[Stbentoak]

I prefer the Walmart DEF because each bottle has a date on it. I can usually get a jug that is less than a month old. I watch my Bank IDash and when I get below 50% I add another jug.

They go through skids of this stuff every week. You couldn't find an old bottle if you wanted to. A bonus to using this stuff is you get a great waste oil jug when you change your oil to take and recycle. Plus, you don't have to deal with pumps at stations that aren't maintained or are dirty. No downside to using Walmart stuff.

 

[Jay P Wy]

Also don't buy DEF from a store that stores the stuff in windows (usually auto parts stores). Two things that will degrade DEF are heat and sunlight. If you store jugs at home keep in a cool place away from sunlight (like a basement).

 

[DaveL]

I prefer the Walmart DEF because each bottle has a date on it. I can usually get a jug that is less than a month old. I watch my Bank IDash and when I get below 50% I add another jug.

Question that is not really about DEF. What do you think about your Bannks IDash and what are your favorite features?
I am waiting for the 2025 Tahoe with the new diesel and have been researching the IDash.

 

[StephenPT]

Question that is not really about DEF. What do you think about your Bannks IDash and what are your favorite features?
I am waiting for the 2025 Tahoe with the new diesel and have been researching the IDash.

There's a lot of things I like about it - in no particular order:

1) It shows me when I'm in a regen cycle. I never want to stop it in the middle of a regen - if I can avoid it. I know it's designed to handle it, but if I can take the long way home and let it finish its regen cycle, plus let the exhaust system cool down a bit, that will help extend the life of everything. It can't be good for the system to shut down at 1100F+ inside the DPF...

2) I like to see engine oil temp. This engine runs hot - the coolant is often in the 210F range and it's used to cool the engine oil in a stacked plate cooler mounted to the side of the engine. Hot coolant means there's less delta T between the two fluids so therefore engine oil stays hot. I see oil temps at ~220F unloaded and above 250F most of the time when I'm towing. I saw 260F once, but then promptly saw the coolant plummet to 185F so that must be a threshold programmed into the ECM.

3) I get to see what gear I'm in. It's amazing how little this engine needs to downshift to go up inclines. A testament to how well this engine produces bottom end torque.

4) DEF level is a percentage and not a little chiclet on the dash info screen. As previously mentioned, once it's at 50% I dump in another jug.

5) Multiple pages for different configurations. I have one page setup for everyday driving - the other page setup for towing. You can have up to 5 pages configured.

6) Last but not least - I like its profile/size. I don't want a mini-tablet on my a-pillar. The IDash has a clean look, easy to read and is a subtle addition to my dash layout. My wife does not like clutter and this doesn't bother her in the least bit.

 

[DaveL]

There's a lot of things I like about it - in no particular order:

1) It shows me when I'm in a regen cycle. I never want to stop it in the middle of a regen - if I can avoid it. I know it's designed to handle it, but if I can take the long way home and let it finish its regen cycle, plus let the exhaust system cool down a bit, that will help extend the life of everything. It can't be good for the system to shut down at 1100F+ inside the DPF...

2) I like to see engine oil temp. This engine runs hot - the coolant is often in the 210F range and it's used to cool the engine oil in a stacked plate cooler mounted to the side of the engine. Hot coolant means there's less delta T between the two fluids so therefore engine oil stays hot. I see oil temps at ~220F unloaded and above 250F most of the time when I'm towing. I saw 260F once, but then promptly saw the coolant plummet to 185F so that must be a threshold programmed into the ECM.

3) I get to see what gear I'm in. It's amazing how little this engine needs to downshift to go up inclines. A testament to how well things engine produces bottom end torque.

4) DEF level is a percentage and not a little chiclet on the dash info screen. As previously mentioned, once it's at 50% I dump in another jug.

5) Multiple pages for different configurations. I have one page setup for everyday driving - the other page setup for towing. You can have up to 5 pages configured.

6) Last but not least - I like its profile/size. I don't want a mini-tablet on my a-pillar. The IDash has a clean look, easy to read and is a subtle addition to my dash layout. My wife does not like clutter and this doesn't bother her in the least bit.

Thanks for all in the info!

 

[JayceeP]

Also don't buy DEF from a store that stores the stuff in windows (usually auto parts stores). Two things that will degrade DEF are heat and sunlight. If you store jugs at home keep in a cool place away from sunlight (like a basement).

How do summer temps impact DEF when it’s in the def tank of the vehicle?

 

[Jay P Wy]

How do summer temps impact DEF when it’s in the def tank of the vehicle?

So far no issues with the Tahoe but the 21 Ram/Cummins I had did have issues with DEF going bad in the summer. I usually only keep the DEF tank half full unless taking a long trip. If you have a Banks iDash or Edge CTS you can monitor DEF percentage (should be around 32%) and see if it's a problem. Sloshing around in the tank as you drive may also help.

 

[StephenPT]

So far no issues with the Tahoe but the 21 Ram/Cummins I had did have issues with DEF going bad in the summer. I usually only keep the DEF tank half full unless taking a long trip. If you have a Banks iDash or Edge CTS you can monitor DEF percentage (should be around 32%) and see if it's a problem. Sloshing around in the tank as you drive may also help.

Thanks for the heads up on the DEF concentration PID. I glossed over that one when setting up the pages on my IDash. I put it on my diagnostics page and I'll check it after putting in jug of DEF next time - my Yukon hasn't moved for a couple of days and currently it's at 33%.

 

[skydiver]

There's a lot of things I like about it - in no particular order:

1) It shows me when I'm in a regen cycle. I never want to stop it in the middle of a regen - if I can avoid it. I know it's designed to handle it, but if I can take the long way home and let it finish its regen cycle, plus let the exhaust system cool down a bit, that will help extend the life of everything. It can't be good for the system to shut down at 1100F+ inside the DPF...

2) I like to see engine oil temp. This engine runs hot - the coolant is often in the 210F range and it's used to cool the engine oil in a stacked plate cooler mounted to the side of the engine. Hot coolant means there's less delta T between the two fluids so therefore engine oil stays hot. I see oil temps at ~220F unloaded and above 250F most of the time when I'm towing. I saw 260F once, but then promptly saw the coolant plummet to 185F so that must be a threshold programmed into the ECM.

3) I get to see what gear I'm in. It's amazing how little this engine needs to downshift to go up inclines. A testament to how well this engine produces bottom end torque.

4) DEF level is a percentage and not a little chiclet on the dash info screen. As previously mentioned, once it's at 50% I dump in another jug.

5) Multiple pages for different configurations. I have one page setup for everyday driving - the other page setup for towing. You can have up to 5 pages configured.

6) Last but not least - I like its profile/size. I don't want a mini-tablet on my a-pillar. The IDash has a clean look, easy to read and is a subtle addition to my dash layout. My wife does not like clutter and this doesn't bother her in the least bit.

Don’t want to sidetrack the thread…
I have a 2022 suburban with the 3.0. I towed a 4500 pound trailer from Austin to Enid and back for our dogs first pheasant hunt. The truck performed beautifully (way better than my previous 2019 Expedition with eco- boost v6)
I got this with 33k in December. I had about 90% DEF tank when I left Texas. I had to refill def just north of the Texas border (50 miles till limp mode).
This seemed like a lot for only about 650 towing. I was driving faster than I used to drive the Expy (avg75mph) and still got 12mpg (compared to 7.5 mpg on the expy)
I definitely have picked up a lot here about def.
I just installed my dash this past weekend. I would love to know what sensors you have on your daily driving page as well as your towing page.