I decided I would try something very different. A Full Synthetic 5W30 Euro by Nulon.
Well the Nulon Synthetic did not last long.
I'm not surprised...happy to be corrected...but reading Nulon's data sheets in the links provided, caution the use of this product in motorcycles. Within the FAQ's for this product it advises the user to read the product label with specific reference to boats and motorcycles in connection to the additives within the product.
This product contains additives suitable to use in my diesel which is fitted with a diesel particulate filter (DPF)...if you then read the info on the actions of this additive suitable for vehicles fitted with DPF's, it rapidly become apparant that the additive within this product will, in all liklihood, have adverse effects on vehicle that incorporate a wet clutch.
Nulon provide a semi-synthetic oil which functions satisfactorily in ST's.
Incidently, is it perhaps worth concidering the short and long term effects of these additives that may have been absorbed into the clutch friction linings?
Just a thought, the can :-)