I've never found leaks a problem on British bikes so long as no one has levered a screwdriver in the joint face (as many seem to do
) or stripped the threads
, or its a pressed primary chain-case which are just about impossible to keep oil tight
. The original gaskets were thin and the period replacements were little more than brown paper so joints always showed some staining and the odd weep but then a lot of shafts (gear change, kick start ) had no oil seals. But a slight oil film was normal and not unwelcome and kept the bikes corrosion free.
I don't subscribe to the modern trend for bone dry machinery, bikes cars what ever, I like to see a bit of oil.
My old Land Rover is still going strong at 54 years partly because the rope crank seals and direct-to-outside engine breather have kept the chassis moist with oil. If I look underneath and there's no oil, that's when I worry. The "leak-a-bit-check-oil-weekly" cars and bikes will outlast the "bone-dry-top-up-at-10,000mile-service" cars.
