GC 0W30 vs. M1 0W40

[Jay]

quote:

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Originally posted by TooSlick:
...All things being equal, it IS desirable to minimize or eliminate the use of VI modifiers. As they thermally decompose, it leads to oil consumption and varnish deposits that cause ring and valve lifter sticking...

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As they thermally decompose... this isn't the same as shearing. So if an oil shears but doesn't thermally decompose then shearing isn't a problem?