Skimming through the last few pages of this thread (I haven't been keeping up with it), but man,,,there is sure a lot of disinformation (some of it Russian disinformation) in it..
There is no instance , no environment, no set of operating conditions where an 0W20 oil outperforms / protects the engine better than an 0W40 oil,,,, not a single one.
Literally anything the 0W20 oil does, any lubrication or protection it provides, the 0W40 does at least equally as well or better in 100% of use cases.
Can an 0W20 oil work,,,, under ideal conditions it certainly can and has been. Anything other that perfect / ideal conditions the 0W40 oil will provide more/ better protection
Can 0W40 cause any issues if used in place of an 0W20,,, nope, absolutely not. The one and only downside to 0W40 is a very, very slight reduction in fuel economy, that's it, nothing else.
0W20 oil was and is spec'd by GM for one reason,,,, CAFE standards. If they don't meet the standards set by our tree hugging government , then they get fined/ taxed. GM is a business, and all business's are in business to make money, so they do whatever they can to meet the standards/ not pay fines or taxes.
Its not a hard concept, and not hard academically to understand. Pretty basic if you have even the slightest clue, which a lot of the loudest voices in this thread do not have.
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