I don't think people are being misled. People can do what they want. There all grown up.I disagree. People shouldn't be misled and waste money on something that isn't proven.
Oil is like one of the easiest thing to test. They know what they put in it and they can tell how much it's broken down .
The thing that always get me is why they think the car manufacturers want to ruin their engines ? Where's the Benifit?
Miles is a very crappy way to measure oil usage. That's why commercial vehicles have hour meters. Those engines earn money. People can't wait for them to fail.
10,000 miles of highway miles is very different than 10,000 miles of stop and go. 10 of 2 mile trips per week is very different than one trip of 20 miles.
Manufacturers also seal transmissions and say that the ATF is "lifetime". Their definition of lifetime. Everyone who ever cracked an Auto trans open knows better.
There will never be a "official" study because no one with the money to conduct one has any interest to make engines last forever. My unofficial study is my Nissan in the driveway with over 370,000 - owned since new by me.
Most people will never put more than 150,000 miles on their car anyway, so this entire debate is mostly academic. Gives people something to argue about.