Syns have been around "publicly" since the '60s (military used it before then. Amzoil has been around since mid '70s. Mostly fleet cars used "syns" to save maintenance costs.
I agree on the mileage taking it's toll on the oil. Plus if his car was a "show-piece" it probably didn't see alot of stop & go and climate changes.
I'ld still like to hear an actual user not a salesman.