Blimey that low eh, I was usng a 50/50 split of 7.5 and 15 wt in mine with about 130 from memory, but no idea what was in the A bike as difn build them but suspect pretty heavy oil
Im surprised you had a leaking seal in such a short time Simon, & there must be something amiss to cause the vibration, I'll be interested to know what you find.