Copper Corrosion Testing of motor oil?

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Please excuse me if I'm being redundant, but I have a clarification question about this topic.

A fellow BITOG member posted the text and photos of the article titled "Comparison of 0W-20 Engine Oils - ATO24 Oil Analysis - 0W-20 Engine Oils with VW 508 00/509 00 Approval" ( https://bit.ly/2P742tC ). The post is located here: https://bit.ly/3uzLoL7

In the photo I have attached, there's one thing that jumps out at me which is the Copper Corrosion Test ( https://bit.ly/3uzoPGw ) results of the Mobil 1 oil, which is graded as "4b" and second from the worst possible result of this test! All of the other oils were graded as "1a", with the only other exception being the VW oil which was graded as "2c".

Since the engine bearings contain copper, this would seem to suggest that this oil is just awful when it comes to interacting with bearings...would it not? This seems really odd since this seems to be regarded as an, otherwise, great oil. Am I misinterpreting something?

Ed
 

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  • Oil Analysis_0W-20_VW_50800_50900.pdf
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  • Oil Analysis_0W-20_VW_50800_50900.jpg
    Oil Analysis_0W-20_VW_50800_50900.jpg
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Just looked at the construction of a bearing. Copper is usually under 1 or 2 or 3 layers. If the bearing wears to the copper, I think you have other issues to worry about.
It might be more relevant to copper coolers and copper shed off those.
 
What ASTM test and the test details/parameters? Sounds a bit fishy and can't read the picture. Or, M1 really messed up that one! I would've been impressed if they gave all those oils the fancy 1-arm bandit Falex/Timken friction tests. 🤣

Castrol was the supplier of the OE dealer bottled fluid, but not the factory fill. So, why are the same fluids drastically different in the same test, but pretty much the same within lab accuracy for other data points?
 
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