I've got Castrol Power 1 Racing 4T 10w40 to go in, my bike has had Silkolene Super 4 semi and Comp 4 semi put in at services it had done by previous owners at main dealers.
Another +1 for Castrol full synth. I'm using it on my Speed3 and SWMBO's Street3. There's been a number of reports of full synth causing clutch problems but we've not experienced that so far. However I'm not sure if full synth is a bit OTT for us, only do about 5000 miles per year and don't give the engine a hard time (it's a while since I last saw the gear change lights come on), so might be inclined to try the semi-synth next year.
The secret with oil is to change it regularly. Mineral oil decays with time, that Includes semi's. Synth doesn't, so if you only do 1000 miles a year you can afford to leave in for 5 years. However.... Acid is a by product of combustion so all oils are made alkaline to compensate. The oil soaks up the acid but when it's full, it's full. The oil is not all about lubrication, it's also about holding the contaminants from combustion, those that slip past the rings. So by regularly changing the oil you keep your engine clean, and hopefully free from the corrosive effects of acid.
I used halford's own brand once because I was feeling tight. If I didn't use the bike every day it glued the clutch plates together. Caused an almighty 'crack' when you dropped it into first from cold, far better if you warmed it up a bit. Won't be doing that again.
Its the clutch problems that worry me mine is very nice dont even clunk into gear would like to keep it that way
Although my petro chemist friend insists there's no difference in levels of protection amongst most brands of oil, there's a huge difference in 'feel' as you ride the machine. Mobil 1 was probably the best I used.
As an aside, when I enquired about having my V8 rangerover engine rebuilt by TVR, it was pointed out that using anything but mineral would void the warranty!!
Bellray 10W40 full synt. Its what she came with. Altough i do have a “klunck” putting her in first. Would semi be “better” then?
The single most important thing imo about oil types and lubrication is the frequency of change. I buy either semi or fully synth whichever is a good deal; but I change it and the filter regularly - twice a year as a minimum and if I've been on a hard trip to the mountains I may well change it immediately on return. Oil is cheap, changing it is a doddle, so why not. I have a spreadsheet on my 'pooter listing all works done and I keep all receipts for oil/filters etc. When I sell on a car or bike I want the new owner to be satisfied that the vehicle has been well looked after, I get better money that way.