Hey, I'll jump into the water here! One of the comments you will hear is to avoid synthetics in older motors because of the sealing issues. Synthetic oil, although almost all of them begin life as a dino oil, has very consistent molecular properties and seal weeping/leaking has been reported.
I'm thinking about changing over to one of the Shell Rotella oils at the next oil change for my airheads. The important additive for our engines is an adequate amount of zinc, ZDDP I believe. Rotella has around 1200 but I'm not looking at a spec sheet. I've used Castrol GTX 20W50 for years but have recently learned that it is lacking the robust zinc properties required.
For my oilheads, I'll probably use one of the synthetics.
OK, who's next?