Here's a thought, GM started putting Mobil 1 in corvettes coming off the line a few years back. Would a car maker spend the extra $ if there wasn't a benefit to be had.
If you look at the molecular structure of syn oil you'll understand why it's a better lubricant.
Now do I think it's better for an old AD motor, maybe if it was a fresh motor, but I can't see how the benefit will be seen in an old leaky half wore out motor, plus a higher viscosity oil is needed for those old motors because tolerances were greater back then as opposed to present day motors.
The best choice I see is to keep clean uncontaminated oil in your motor. The choice is yours as to which one.
It's going to take a lot of miles and a complete tear down to determine which oil is actually the best and then by what margin was it the best.
Dan
