I don't keep my vehicles long enough for a story like this of my own, but my Dad's '01 Implala has nearly 300,000 miles and never an internal engine repair. Oil was changed regularly, and it never saw anything more than the "bulk" dino oil that Pit Stop USA, Oil Can Henry's, etc. use.
For every high mileage story from a synthetic user, there is at least 1 similar story from dino oil users (probably more like a dozen due to market share). The one thing they ALL have in common though, is regular oil changes.
I found this related article very interesting and seemingly unbiased...
Separating Facts from Friction | Best Motor Oil | Consumers Digest | Motor Oil | Consumers Digest
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2013 Rockwood 8289WS w/Diamond pkg
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)