boxer engines use a dry clutch so they can run on car spec oil!!! i pay 16 quid for 4 litres shell advance 10w 40.use a halfords or garage forecourt own brand motorcycle oil as long as the the jaso specs are ok thers no problem as it has to meet stringent standards to meet the jaso spec.lots of oil brands are just marketing exercises anyway just check out the specs on the back of the bottle and look at the specs on the cheaper brands-there aint much difference!-buy cheap and change it a bit more often.