I've never understood the "great oil debate". It seems to exist among airplane owners, motorcycle and auto owners. The fact is these bikes will work just fine on any decent brand of appropriate oil. Wet clutches have been around for decades and been operated using oils far less sophisticated than available today...successfully and trouble free. I use Castrol Act-Evo 10/40. It appears to be a simi-syn(?) I'm not married to it and might change over to full-syn in the future, but I'd bet a BA or Speedy would run forever on it (or at least as far as on any other brand).
