Personally I used to be very interested in every new oil supplement that came along although I actually used only a few. I can remember that one I considered using was a supplement that contained Moly. It was a good thing I did not actually use it because it was the wrong kind of Moly. Now there is Moly in a suitable chemical form in most new motor oils.
Really the only oil supplement or engine cleaner that I believe in today is Auto-RX. Auto-RX seemed to work for me and it can even be used to clean transmissions, power steering units, and probably transfer cases and differentials although I have not tried it in any of these.
I personally think that 99.99% of all oil supplements are useless. You are better off using a good quality motor oil and changing that motor oil at reasonable intervals. The big decision is whether to use conventional or synthetic oil.