Some people say that M1 isn't a true synthetic either since the lawsuits. I say they are splitting hairs off a dead horse.

With good maintenance you can make your engine outlast the rest of the car with either one of these oils. There of course will be a few exceptions. This would probably also be true of many other oils on the market.

Now note that there are bigillions of posts in existing oil threads on this forum and oil threads have a history of going off topic or digressing into opinionated speculations. If that isn't enough to wear you out check bobistheoilman.com.