With all due respect
@jfoj, if GM is going to inspect 6.2's, and if they pass, change the oil spec to
Dexos 0W40, and extend the warranty on the engine to 10yrs, 150k miles; recommending someone
not run the dexos approved oil is setting them up for a disaster if this remedy turns out for GM to be a bad one and a bunch of 6.2's grenade at 95-100-115-120k miles.
"Oh, we told you to use Dexos 0W40; you got your service records?" You respond, "Sure, here they are..." GM says, "Oh, You used AmsOil 0-40, not dexos approved...you didn't follow our instructions."
We know and appreciate your opinion on the oil situation; but I think the odds are there is more to the story. Regardless, we also know that it will be key to follow, at minimum, the engine oil requirements from GM as long as this engine is under warranty. Recommending going outside the Dexos cert is not something I think one should recommend.
My guess is the bulk of the bearing fails are actually due to the "out of tolerance machining" on the crankshaft that GM has admitted to. Think about it, engineer designed the rods and bearings assuming a given diameter of the crank, crank is off by 0.001 or .002 or .003. If it is too tight, can't get enough oil in there, if it is too loose, you are banging the bearings into the crank...either way...eventually a kaboom. The heavier oil would protect against too loose (crank over machined), probably doesn't help much on the too tight...maybe it does...but probably not. This too loose scenario would be exacerbated by the low RPM, High Load situation these motors are operating at in our trucks.
