A lot of what oils contain is a secret because most oil brands like to keep it that way to keep the competition guessing.
Some come out and tell you, like Valvoline for example who posts on their website that their Syn-Power oil is made from primarily GRP-III base-stocks.
Then there is our good guy Johnny who used to work for Pennzoil and is retired and can confirm what Pennzoil products use for base stocks for you.
Mobil-1 dances around this question every time someone asks them via their website or support phone number, this is balanced by some of the M1 nuts on the board who think it's gods gift to engines... It's highly speculative and can't be confirmed. (It's a very good syn oil IMO, just not "the" only good syn oil as some would have you believe.)
In the end, it doesn't matter what the oil contains IMO, so long as it gets the job done. The only way to test if an oil worked is to keep using it and drive your car as long as you can.
All oils today including SM rated dino are great quality and will offer 99% of vehicles on the road the protection they need to see a longer life that you imagined or wanted.
Unfortunately in the US you aren't as big on rust-proofing as we are in Canada, so most likely Rust will get the car before the oil gets the engine!
IMO you should use whatever you can find on sale that meets the specification for your engine and the demands your driving habits, climactic conditions and all other stressors place on the oil. Change at a reasonable interval and keep your engine running in top-order with tune-ups and other regular maintenance and this will surely return you many trouble free miles.
It's not rocket science! It's as simple as: A + B = C