you only have to oil one side- the exposed side obviously lol. ive seen guys oil both sides with the result being oil sucked into the plenum because its been over- oiled. you only need enough to stain it red (the oil colour) and dull out any sun light when you hold up towards the sun for example. and yes tinny they are k&n filters that vcm use. its actually a mercedes filter,just a bit of useless info there..