GM aborting move to 0w-40
- Thread starter dbias
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I think in many cases = Profits
(not saying this is true for everything but ...)
Purchase components from a reliable supplier called ABC but then a company called DEF comes along and says we can produce this (or these) parts at a better price. GM goes back to ABC and says DEF is offering a better price. ABC says they cant do it so GM goes with DEF and then the trouble starts.
Then there is BITOG ...
where people claim that 20 weight oil protects the same as 30 or 40 weight so the maker of parts that GM contracts with tries and sometimes fails to produce a more wear resistant part to be used with lighter oils.I couldnt bring myself to put the called for 20 weight oil in my wife 2012 SkyActive Mazda when we bought it. I used 5w30 for 12 trouble free years. The car has been sold to someone in our community recently in perfect running condition. It has never needed a repair since 2012. Even Mazda stated outside the USA 30 weight could be used if 20 not available.
Keep in mind we do live in the warmer southern USA so I am 100% comfortable using 30 where 20 is called for. Im just not convinced on 20 weight. In a perfect world maybe it's ok but then again, in reality 30 is not all that much more thick and the viscosity of any oil is much more heavy by many times before an oil is up to full operating temperature. I feel in a warmer climate my thinking is correct for a 30.
Another example, just like GM suggesting a 40 weight in engines that check out ok. There is something to be said about a more heavy oil. Another example why does my 2017 GM 6 cylinder SUV with a tow rating of 5,100 LBS SUV call for 5w30 instead of a 20?
Now if I lived in a super cold climate, wintertime maybe I would be ok. But I HONESTLY think most all of this light oil (which in many, many cases is ok to use) is only for USA EPA mileage requirements.
Toyota was the one that surprised people. GM has been making trash since the GMT 400 platform debuted, and gosh that was 1988. It would take reams of paper to list all the common issues we've seen on GM trucks over the last 35+ years.
As far as this specific issue goes, GM says that the 2025 engines got "updated parts" that will prevent these rod bearings from being wiped out. I personally don't trust that after my experiences with GM.
But yeah, I think this is a combination of oil spec and poor parts. GM isn't the only OE to have issues with 5W20 or 0W20. Look at how Ram had a bulletproof 5.7L V8 for years until they started slowing dropping the viscosity spec...and then cams and lifters started going bye bye.
Incoming QC sampling plan should catch that. I don't know but guessing ISO/TS IATF 16948 + 9001 QMS is pretty robust.
I would also think GM is casting/forging and machining their own cranks and blocks and heads
But maybe I am just so 1970's U.S.A. Old Fogey
Not to belabor the point, but it was probably Hyundai/Kia that buggered up the engine manufacturing process first with their Theta engine.
For people that don’t know how serious this is, I found this 60 Minutes piece very eye opening. I had my airbag replaced, but I live in Georgia where it’s humid most of the year. Am I still driving a ticking time bomb?
The new engines are only certified for 0-20.
Connecting rod bearings.
Yeah, I've been sitting on a recall for my 2017 Traverse. I intend to FINALLY have it addressed when I bring it in for a transmission flush.
Its unbelievable that in 2017 this was still an issue
OVERKILL
$100 Site Donor 2021
Bearing shells aren't hardened, they are intentionally made of soft material to protect the hard material of the journal and to allow abrasive material to embed in them so that they don't score the heck out of the crankshaft.
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Correct and if a new engine is not put in the vehicle 0w40 is the new oil recommendation.
Well what caused them to heat up so much that they fail?
OVERKILL
$100 Site Donor 2021
Typically what causes a bearing to fail is inadequate MOFT, allowing the journal to touch the bearing, and if this exceeds the capability of the AW additives (which can tolerate this happening momentarily), the soft babbitt welds itself to the journal, which causes the bearing to spin. This then often results in the connecting rod seizing, so the whole piston/rod assembly stops rotating around the journal, resulting in it being forced into the side of the cylinder, breaking the wrist pin off the piston and shoving itself through the side of the block, windowing it.
MOFT was too small with 0w20.
I belive in to big tolerances and bad finish and there a thicker oil will make it last longer but not so long that a well built engine with the right tolerances would be holding up. The 0w40 may just be a way to give GM a little longer time to built enough engines for replace the bad ones
OVERKILL
$100 Site Donor 2021
*clearances.
Tnx for correcting my bad English
OVERKILL
$100 Site Donor 2021
No problemTnx for correcting my bad English
It's not like they were blowing up immediately on 0w20. Normally antiwear additives would pick up where viscosity can't quite handle periodic high load/dilution but if it's working as designed there isn't any metal to metal contact.
But if they did fail we know there was metal on metal contact, which means inadequate oil pressure/thickness for whatever was going on, leading to the heat he asked about.
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