I use texaco moly horrid black shit on mine never been a problem it's just to keep water out I think , http://www.ebay.co.uk/itm/251354946521
I've used it for a couple of years now on the joint and I smear it all inside swing arm as well just to try and keep any corrosion at bay
the proper stuff,and its very good as rec by bm is
staburags nbu 30 ptm,its a very thick sticky grease and very water resistant,available on ebay,the stuff recomended above by comparison is runny shit