Mine leaked and i got rubbish seal as part of a swivel kit from dingocroft, this new seal leaked even more than the old one :wtf:
Im using 80w/90 oil in the swivel which is not THAT thick, i perservered with the oil even though i got hold of some of the grease as per prior post, but i never used it, and after about 3000 miles the new seal has virtually stopped leaking oil, so i guess it has probably worn in. It seemed a pretty hard rubber so maybe thats what was needed. It must have leaked over a ltre of oil out before getting worn in, but none ever got on the discs.
I had the hassle of draining/refilling the swivel with oil for each 6 monthly wof check to make sure it passed, but im happier running with oil in the swivels as at least i can check how much is in there.