They used to be sold dry (white element) but folks were a bit dumb and neglected to buy and apply the red filter oil. Now most come pre-oiled - and of course ppl are still a bit dumb and neglect to clean and re-oil as needed.
There is a K&N filter cleaning and re-oiling kit available for around $15.00:
... but I'm cheap so I wash the pods in solvent until they are close to white then with water and laundry detergent to get the solvent out then hold each on a wet/dry vacuum until dry, maybe once a year (sucking the solvent out leads to unpleasant vacuum explosions). A squeeze bottle of K&N oil lasts about forever for pods... not so long on a large car filter.