All fatty substances, even purified will "turn" rancid with age, I believe
due to oxidation. I'm not convinced that the seals on the usp purified
lanolins can be totally sealed from air leaks.  I have also noticed, since
our whole (5 folks) family uses this stuff for everything and leaves it
every where, it develops a stronger odor, not offensive, but stronger !!!!
Sue H. any input ?