Old synthetic oils were not compatible with neoprene - hence leaks. (crowd I hang with refers to this as a myth originally founded in fact.. a long, long time ago).
Model A does not use neoprene, and those old synthetics are no longer made.....
(why are we worried about leaks with a Model A??)
Dino has a shelf life shorter than synthetic, but you do change your oil.... right??
I had the opportunity to partake in a tear down of a modern engine for warranty work - engine ran 70,000 miles on Dino - this was my company truck. Warranty issue was corrected, and engine checked for wear - no measurable wear was found, all within initial spec - engine presented as if it had only a couple hundred miles on it . I used to spend money on synthetic, I do not anymore. Nothing against synthetic, just not sure I was getting anything for the cost. YMMV depending on how and what you drive.