WOW, I've seen this discussion a few times, and the text always reads the same.
As for me, I've used nothing but synthetic in EVERY engine I've owned over the past 20 years. And I would never consider ever changing back. -and by the way, some engines brand new, and others switched at high mileage. -one, at 198,000 miles, and it now has 233,000. -still no leaks, no burning, etc. On some of my new engines, it seemed to take a VERY LONG TIME for the rings to seat, which I just sort of "wrote off" to the synthetic. BUT, I can't prove that.
I guess as I see it, there is absolute no magic involved at all. (-although the myths always flow freely,,,). For me personally, it boils down to these few considerations:
1. There is no doubt in my mind that synthetic lubricants are superior in every way. (anyone that really wants to "dig out the facts", should do the research. The facts are out there.)
2. In almost all applications by the "average consumer" there will be no real measurable/provable advantage. Standard lubes will work just fine.
3. The extreme cold weather properties are VERY advantageous. (-and they stand up better to high temps too, I'm sure).
One of my applications was an old 4-wheel drive truck, used daily during zero-degree winter weather (Northern Wyoming). I changed to synthetic in both differentials, transfer case, transmission, and engine. There was a "night and day" difference in the reduction of "viscosity drag" on those sub-zero mornings.