Longevity of dino oil compared to synth? Bah...
'93 GMC -- 5K oil changes for 177K miles. Maybe 3 of the changes were with synth. The rest were dino oil. Mostly AC Delco filters. Used STP a few times. No ill effects observed. Of course, this isn't based on any real research or testing. I don't have any blow-by. No oil consumption. Oil comes out brown when draining. No oil leaks in or around the engine.
'05 HAH -- at 5K, did an oil change with Honda dino oil and Honda filter. Will probably continue with the 5K oil change interval. Maybe with M1 5W-20 and staying with the Honda filters. We'll see...