If looking for lubricity, a bit of TCW-3 2 cycle oil cant be beat. It is clean and easy to dose, and so long as you dont buy the garbage walmart stuff, it generally doesnt smell bad either.
The best results I found was with Rotella DFA.
If you have a cleanliness issue, or wish to baseline, I'd run lubro moly diesel purge, set up the right way.
Otherwise, remember that with all adds, less is more. It is important to consider load profile, use characteristics, etc. in selecting what and how much youll apply.