Ive never actually been able to loosen one of these without breaking something. if your going to lubricate it its only temporary but don't use wd-40. wd40 is junk for almost everything. Its not a good lubricant and evaporates quickly. Used a heavy oil like atf or motor oil after cleaning the area with brake cleaner. Or possibly use bearing or lithium grease

__________________
1981 300SD 512k OM603