Yamaha Oil Tank Cap Assembly - 6E5-21770-03-00Yamaha Oil Tank Cap Assembly Oil System 6E5 21770 03 00 Overview This is one of those parts you dont think about until it starts causing a mess or letting air into the system. A good oil tank cap needs to seal tight and keep everything where it belongs, especially on 2 stroke setups where oil flow matters. Ive seen cracked or loose caps lead to leaks and even affect how oil feeds into the motor. Swapping it out is a simple fix that keeps your oil