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If it's a K&N filter I believe you just wash it down with warm water. Then you let it dry and re-oil it with a recharge kit (you can get this at an Autozone). You just mist on the oil per the instructions, wait a little bit for the oil to soak in and re-install. You need to re-oil because it traps the dirt in the filter, so don't just wash and re-install. Hope that helps.