You're putting too much thought into this...unless you're willing to invest a decent amount of coin into oil analysis, adding random additives, etc. is pointless because you'll never know whether or not it's worth it.

Do this instead:
1. Choose 3 or 4 decent brands/weights of oil
2. Run them all at your typical oil change intervals
3. Note any noticeable difference (consumption, oil temps, etc.)
4. Pick the one that "performed best" and stock up next time it goes on sale