Do K&N air filters come pre-oiled or must they be oiled before using?

Almost all K&N air filters come pre-oiled and ready to use. They are packaged in a clear cellophane wrapper with the words “Factory Pre-oiled – Ready To Install”. The filter oil we use is red. A new oiled filter will appear red-pink in color. Some crankcase vent air filters come unoiled, however, they come with a small packet of K&N filter oil so they can be oiled before use. There are also a limited number of filters with specialty uses which are not pre-oiled. These items will be clearly marked as unoiled. Using an unoiled K&N filter will greatly reduce the filter’s efficiency and void our product warranty on filters that come pre-oiled from the factory. If you receive a filter that is packaged in its cellophane wrapper and is unoiled, contact K&N’s Customer Support department at (800) 858-3333. more