My understanding (FWIW) is the only / BEST way to determine the actual effect of your beloved oil selection is to have the used oil ANALYZED by a 3rd-party testing facility. I know they are out there, but I've never used one.
Has anyone here ever sent an oil sample to a lab for inspection? Which lab did you use?
I think that some of the data received would include iron/metal content, breakdown of the molecular chain (there's a word for that, which escapes me at the moment), and other factual, chemical results. This will provide a synopsis of the efficacy of your choice of oil, and to some extent how much of your internal motor parts are being / have been worn away.
I understand the tone and reason for the initial OP question.
Some will actually go to the source (in this case, Shell), others will research, and many will become so confused that they continue with whatever brand / lubricant as they always have.
Thanks.
(Joe Friday voice: "Just the facts, ma'am.")