I use a thixotropic oil/grease in my gearbox. It’s got the standard felt seal, a rather rusty shaft and I’ve never had contaminated clutch plates or slipping clutch. The bike gets left, sometimes for weeks, on the side stand. I’ve got Pierce clutch plates but still ferodo inserts in the basket. The springs are Fanny Barnet 250 as the club ones were too heavy with the thicker, modern plates. I must just be lucky 8)
