Bevel drive oil leak R100GS - ideas ???

[Mike Wilkins]

have just noticed this evening the rear half of the final drive is oil stained - not serious, not dripping. I have the impression its coming from an air vent that has a flimsy plastic 'cap' and 'vent sleeve' (in the Clymer manual otherwise no mention). I recently did an 850 mile round trip to the Ardennes beforehand I checked the level and all ok, otherwise only short trips except for the Weekend. I think this has only just happened as I recommissioned the bike this summer and cleaned up all the alloy with car wheel cleaner so any leak is obvious and the Belgium trip I think is the culprit. Is there any reason for the air vent to start blowing oil - seal gone or whatever.
As I said its only cosmetic for the moment but dont want to let something serious to develop
Cheers
Mike

 

[MickDB1]

Just check you put just enough of the right grade oil Mike
GL5 not GL4 also if it were red ot it may have panted a bit onto the dusty bevelbox

 

[Mike Wilkins]

Did not need to touch the oil Mick - not since I first had the bike 3.5 years ago when I changed everything. Just now its started leaking

 

[Rob Farmer]

If you haven't changed the oil in 3-4 years then it's probably all the water boiling off