If you have POS old Motor you can run 50 straight weight and get more for your buck. If you use Syn oil and change it at intervals in you owners manual, there is absolutely no reason for additives...
Damn it Jim, i'm just a country Doctor.
POS? If it runs reliably, I would not call it POS. I try to keep it running as looong as possible. I don't get a different bike until the one that I currently have is (nearly) used up.