This article is from the VW Performance FAQ, by with numerous contributions by Jan Vandenbrande others.
A:You can buy the K&N chemicals (cleaner and reoiler) or
you can use a detergent called Formula 409 (used for
cleaning kitchens in the US) to save some money (the K&N
cleaner is rumored to be the same as Formula 409). You
should always use their oil though. Also do not rinse the
filter in hot water. It'll shrink the cloth.
 
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