first, are you changing your oil or are you taking it to a service station? Because there arent any "air filter inductuctions" in that area. the filter is accessible down the pass side of the block. the only thing it could be after having an oil change down is that your incapsulation panel or "belly pan" is not secured properly and flapping as you drive. just shimmy under and inspect the panel to see if all the screws are there AND that they are secured to the subframe. sometimes one of those screws is left of and they will flap against the subframe giving you that noise. I hope that helps.