What is the seal which fits over the little spigot in the oil feed between the case and the oute, made from ? I think it is supposed to be a tapered seal - mine is a neoprene O-ring. - Can the additives in the oil stuff it ? I just use a multigrade 50 oil in my 850 motor. I can't remember what the 20 means in 20/50 Multigrade. Four-stroke motors get very hot, especially when run on petrol. I sometimes wonder about oil pressure in my 850 engine. When I had Triumphs, I had so much oil pressure that, even after a long race I could not push the indicator button in. Commandos have gear pumps - not plunger. The Triumph crank used to wear like crazy, until I had the journals hard-chromed. I used MIni-Cooper copper-lead bearings. But it was consisrtently revved to 10,500 RPM. - Commandos don't go over 7000 RPM.
I don't know whether I believe in Castrol R - it turns your bike into an instant shit-heap. My mate used to wash his Manx with methanol after racing. I just did not use it after the first time.
My 850 runs on methanol so is probably a bit cooler - it still clicked as it cooled down after it had been raced