Re: How often do you change your oil?
Having considered the responses here (thanks all), and followed a few of the links above, I now have a plan:
December - 5w40 fully synth (nice and runny for the winter, although I expect it will burn more)
June - 10w60 (as this is when the 12 month service cycle falls, and B+W use Selenia as standard I think)
Seems like a good all-round solution to me, and not far off zulu ferrets schema.
Just a quick thought though, is Selenia (racing) a mineral or semi-synth oil? Could muck me up if its a mineral oil. Hmm.