[Darren69]

You can use fully synthetic oil with the dry clutch no risk of slippage. I use Motul 300V 15/50 in my S4 around £15 per litre or I have also used Motul 7100 in the past which is a but cheaper at £10/litre both good oils. I'm led to believe by experts that 300V is probably the best oil, at least for the 4V engines.

Its been so long since I had an air cooled bike, so I don't know which is best and some will advise that it depends on the ambient temperature which weight you use, I would think either of the above should be ok, maybe overkill even.