today i went to put the k&n back in my mom's camry with the 2az-fe engine. and when i looked in the airbox the part that goes on top looked like it had a filter built in to it. has anyone noticed that and is it even a filter? if it is a filter after the drop in filter then i feel better putting the k&n back in there. also while i'm asking this question, how often does a k&n need reoiling? how about cleaning? thanks