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dexosD?


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I have been using this oil exclusively since new. I only have 4200 miles now, but I have noticed my engine has more clatter than it had when new.


I thought it could be a few things like fuel quality but then I figured the oil was thinning out. So I changed it at about 3000 miles with no real difference in sound. 
 

Started looking around for another brand in hopes to find a better oil, and as we all know there are almost no dexosD approved oils on the the market. 
 

So I figured I’d go by the API and SAE requirements and noticed something interesting. The AC Delco 0w-20 dexosD has no rating on the bottle or anywhere that I can find. This top secret oil has very limited information available online as well.

 

I then checked the 3.0 liter duramax owners manual supplement and noticed another strange detail. The manual says to only use CJ-4 or CK-4 rated engine oil or “damage to the DPF will occur”.

 

I have yet to find a 0w-20 that carries this API rating and now I’m thinking that the AC Delco dexosD 0w-20 does not have this rating either.

 

Does anyone know what the hell is going on with the required oil for this 3.0 LM2?

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Go by the info in the 3.0L supplement.  (I'm not sure where you found the cj-4/ck-4 15w-40 info?)

 

GM does have diesel supplement manuals for each of the 2.8L, 3.0L and 6.6L engines

They used to have info for more than one in the same manual -- which made it easy to get info for the incorrect engine..

 

3 current GM pickups with dmax engines, each with it's own engine oil specs. 

 

2.8L -- Dexos2  5W-30

3.0L -- DexosD  0W-20

6.6L -- CJ-4 or CK-4 15W40

 

 

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You have one other option if you are interested in trying.  It is AMSOIL's dexosD oil. 

 

If you want, send me in a PM your zip and I can send a quote on cost shipped to your door.

Edited by Black02Silverado
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Mobil1 ESP X2 is also DexosD rated. Not cheap, ~$13/qt.

 

I went to pick up a couple quarts, as I checked my oil, nothing was on the dipstick, and found the local carquest parts store stocked the GM part number for $5.45/qt. It wasn't listed in their inventory when I checked online.

 

1 quart raised the oil level to the mid point on the dipstick. I think they could have done a better job with that. You should have some indication before it just disappears, like a quart low is the bottom of the tab...

Edited by OldTrix
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12 hours ago, redwngr said:

Go by the info in the 3.0L supplement.  (I'm not sure where you found the cj-4/ck-4 15w-40 info?)

 

GM does have diesel supplement manuals for each of the 2.8L, 3.0L and 6.6L engines

They used to have info for more than one in the same manual -- which made it easy to get info for the incorrect engine..

 

3 current GM pickups with dmax engines, each with it's own engine oil specs. 

 

2.8L -- Dexos2  5W-30

3.0L -- DexosD  0W-20

6.6L -- CJ-4 or CK-4 15W40

 

 

It’s listed in the 3.0 Duramax supplement manual. This is the online version for the 2020 model year.

 

I found my hard copy and this is not the same information listed under the caution for the DPF. 
 

This must have been an oversight for the 2020 model year. 
 

67EACF85-E1CB-4F27-A75F-036A8C5DCEE8.jpeg

Edited by fireaxxe
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10 hours ago, Black02Silverado said:

You have one other option if you are interested in trying.  It is AMSOIL's dexosD oil. 

 

If you want, send me in a PM your zip and I can send a quote on cost shipped to your door.

I was interested in the Amsoil 0w-20 but it says do not use if Ck-4 is required.

 

I am thinking the Cj-4/CK-4 bulletin might be a misprint in the supplement manual.

 

I am also concerned about oil leaks that have been reported like the rear main seal. I’d hate to have a warranty issue because GM wants to blame non dexosD oil.

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6 hours ago, OldTrix said:

Mobil1 ESP X2 is also DexosD rated. Not cheap, ~$13/qt.

 

I went to pick up a couple quarts, as I checked my oil, nothing was on the dipstick, and found the local carquest parts store stocked the GM part number for $5.45/qt. It wasn't listed in their inventory when I checked online.

 

1 quart raised the oil level to the mid point on the dipstick. I think they could have done a better job with that. You should have some indication before it just disappears, like a quart low is the bottom of the tab...

I have heard that a few people have been just over a quart low on these. My oil level has never been low since new. They may have came from the factory a quart low due to the interruption in manufacturing and all the shortages that occurred during production.

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  • 1 month later...

I went with the Mobil 0w-20 x2. The oil is physically green in color with the DexosD label on the bottle. After the change I noticed the cold start was dead quiet. Once warmed up the fuel knocking was at a much quieter but still there. I got my hands on a gallon of 5w30 Delvac Mobil 1 and topped off with 1 quart. The fuel knocking sound is gone. But went into regen and all the knocking and clatter returned but nowhere near as loud as it was before the oil change. I think the basic 0w-20 is just too thin for the diesel even if it is a light duty design. I plan on getting a UOA once I change it again.

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On 12/1/2021 at 4:25 PM, fireaxxe said:

I went with the Mobil 0w-20 x2. The oil is physically green in color with the DexosD label on the bottle. After the change I noticed the cold start was dead quiet. Once warmed up the fuel knocking was at a much quieter but still there. I got my hands on a gallon of 5w30 Delvac Mobil 1 and topped off with 1 quart. The fuel knocking sound is gone. But went into regen and all the knocking and clatter returned but nowhere near as loud as it was before the oil change. I think the basic 0w-20 is just too thin for the diesel even if it is a light duty design. I plan on getting a UOA once I change it again.

XOM makes/blends  the ACDELCO Dexos D 0w20 under contract  and I suspect both are the same chemistry.  The green color is a dye. Not functional. 

The engine was designed for low dynamic vis to operate properly. It does not need a heavy minimum operating film thickness to function correctly.  HTHS testing has limits for that in diesels and Dexos D can be as low as 2.6 .  In other words more viscosity is just a drag on the design. For instance FK4 spec for fuel efficiency on HD engines allows 2.9 at 0w-30 grade. CK4 requires 3.5 min.  Overkill and potentially needless heat holding viscosity dynamically. 

 

I have tested both the Mobil made AC Dexos D 0w20 and Amsoil DP 0w20. I saw better results with the Amsoil DP 0w20 product. Discussed elsewhere on this site were a couple of oil analysis results on newer 3.0 diesels and the Amsoil results I have interpreted  improved wear, soot handling, also lower fuels dilution vs the AC Delco product. 

 

I suspect from the chemical make up of the Amsoil they are using some bio synthetic base oils to exceed the standard while XOM is relying on synthetic to meet the Dexos D spec.   That bio component can solve out soot that the filter and engine oil cannot disperse. 

 

CK4 and CJ4 have limits on deposit forming and DPF killing organometallic additives that will sinter into your DPF ruining its ability to clean up. Like welding metals into your ceramic DPF substructure.   Sulfated ash testing is how they judge the metals in the oil additives limit.  See CK4 limits.  

1812148617_ScreenShot2021-12-03at09_24_39.thumb.png.90c8dd40dfb60b358c8e8b38885034cb.png

 

GM specs Dexos D 0w20 to a limit of 0.8% max sulfated ash.  For the DPF not to be permanently damaged. 

 

Most likely the Delvac 1 5w-30 qt you added has 1.0% of what would test as sulfated ash and most likely blows through the phos and sulfur limits  so I do not recommend that being used consistently.  Understand you needed a top off and its a great oil but if you are using any oil that chemistry will sinter into the DPF. 

 

Frequent regen cycles are usually a sign of issues with the DPF not cleaning up enough. 

 

@4200 miles complaining about excess sound on this engine is subjective but I am betting its fuel related not engine oil. I do applaud you for pulling a oil sample and get a lab that does KF water testing and GC fuels with a full battery of FTIR work or you are flying blind. 

 

 

 

 

 

 

 

 

 

Edited by customboss
typo
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On 10/23/2021 at 11:47 PM, fireaxxe said:

I was interested in the Amsoil 0w-20 but it says do not use if Ck-4 is required.

 

I am thinking the Cj-4/CK-4 bulletin might be a misprint in the supplement manual.

 

I am also concerned about oil leaks that have been reported like the rear main seal. I’d hate to have a warranty issue because GM wants to blame non dexosD oil.

The 3.0 requires dexosD and AMSOIL's 0w20 oil that I posted is specifically designed for the new Duramax 3.0  The reason it states don't use where CJ-4/CK-4 is because some might try to use it in other diesel engines just because it is a diesel oil.  It is specifically for the dexosD application.

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