If you watch the Lake Speed Jr video about this GM engine recall, it's the journal bearings that can fail and potentially cause catastrophic engine failure. It's a voluntary recall, and seems to be safety related because GM doesn't want these engines potentially locking up from major rod failure on the roads. KIA has a similar recall about engine journal bearings failing and engines blowing up on the road, and potentially causing a dangerous situation. Believe they also too spec thicker oil. Seems some of these auto manufacturers are learning the hard way of the ramification of trying to run the thinnest oil possible.I don't think the problem is the engine in that case. I thing it's CAFE. Those engines apparently weren't "problematic" before they mandated 0w20 in 2021. Maybe a failed example here and there like everybody else but not at pandemic level like we see now. My guess? With 0w40, you will not hear anything about failed bearings in those 6.2 like we hear now. It's only a guess but i think it's a good one.
LSJr explains why GM went from 0W-20 to 0W-40 in this case to mitigate the issue. Just like in every journal bearing spinning in the world, the oil viscosity needs to be adequate enough to prevent metal-to-metal contact and wear. We know in the world of EPA and CAFE, that most of these engine designers try to go as low as possible and still retains some engine reliability and longevity, but it doesn't always work out that way. Ford bumped the viscosity up from 5W-20 to 5W-30 in 2021 for the Coyote in the USA, not just for fun, but only be one reason ... better engine protection.
So in the case of these 2021-2024 GM engines, even though 0W-20 has been specified in the past and seems to have "worked" for the most part, these particular engines don't really like that thin oil in all cases. Is the root cause a slight manufacturing issue? ... could be, but looks like going up to a 40 grade is something the engineers of the motor believe will cure the issue. If engines in use exhibit a trouble-code P0016 then that's a sign that the bearings are becoming worn out and the fix is to replace the engine. If there is no code P0016 then the oil is swithced to 0W-40 (even on brand new trucks sitting at the dealerships). So GM is now ignoring CAFE and listened to Tribology and putting in the oil viscosity these engines probably really need to properly protect the bottom end.