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.
Yes I have driven awhile and the truck is still smooth slowing down from 25mph. The main thing that solved this problem for me was removing the SQUARE lift blocks that came with the GM kit. I then replaced them with a TAPERED 2.25” lift block. I have removed the 3mm washers I installed between the transmission mount and transmission and noticed little to no change.
According to those calculations when I refilled it I had a total of 4.5 gallons then drove 1800 miles. I noticed that the manual list the total tank size at 5.3 gal. It makes sense that the last full bar represents 1.8 gallons of def when at full capacity. However I’ve towed for about 300miles and drove in various conditions for another 1500 miles and I’m thinking it should have used over gallon of DEF.
For those of us using the Amsoil dexosD oil. How do you like it? Has anyone done any UOA? Difference in performance or MPG? How does it sound? Any difference in engine clatter? Lastly, what’s the oil consumption rate if any?
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.
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.
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.
I have the same clatter, fuel knock, and pinging with mine as well. I notice it’s really sensitive to different fuels with BP causing the worst sounds from the engine. Love’s with 7 oz. of Stanadyne additive gives the best results for me. I’m also thinking the oil is way to thin for these diesels which is contributing to the noise.
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?
Just picked mine up from the dealership and was informed that they were able to recreate the crank no start issue and they “fixed” the problem. I was then told they updated the software and instantly my excitement faded away. They also did something to the regen cycle. It was in regen on the way home and I heard no knocking. In my state it takes 4 repair attempts and 20 days at dealership for the same issue to use lemon law, so one down 3 to go. Due to the fact that I am interested in a buyback I have to record every time I hit the start button for proof. Will post updates.
I have also seen the “Service steering column lock” message but it was when the wheel was turned and once I put pressure on the steering wheel to take the weight off the column lock I heard it click and the truck started just fine. Message has never come back.
I am FULLY aware there are no spark plugs in a Diesel engine. This is why I specifically said FUEL KNOCK. The timing of the Diesel engine is determined by the fuel delivery to the compression of the air that generates heat in the cylinder. In order to know when to deliver fuel the ecu looks at a number of sensors specifically the crankshaft position sensor and camshaft position sensor. So to reiterate my point, if there is an issue with the cam sensor this could cause not only a no start issue but also mistiming of the power stroke causing fuel knock and engine damage. I don’t think the 3.0 duramax has VVT The fuel was tested by a lab and was good and I only have a few thousand miles so no chance of significant carbon build up to cause a fuel knock. There is something wrong with these trucks.
There is something seriously wrong with these trucks. Yesterday while driving it went into regen and the engine was making the most god awful fuel knock I have ever heard. I am guessing if the cam sensor or reluctor/exciter wheel is the issue with the no start then the timing must be off while running at times as well. This would explain the fuel knock. I don’t believe the crank no start is the only issue related to this problem. There is no way this aluminum diesel will hold up to that. Yesterday I went to my purchasing dealer and requested a buy-back.
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