Friction reducing additives are all nonsense. Usually PTFE based, they eventually block up oilways and cloge filters, causing more issues than they could ever hope to prevent. Avoid, and use decent quality oil of the right grade
I would never add anything to my oil, if you use good quality stuff in the first place you would expect it to come with everything it needs to perform anyway.
Opie oils did a thread about additives on CS last year, interesting read.