A locking assembly includes a release mechanism and a cap. The release mechanism includes a pin. The cap threadingly engages with a fill neck and includes a barrel portion and an engagement portion. The engagement portion radially surrounds the barrel portion. The engagement portion presents engagement threads which threadingly engage with threads of the fill neck. The annular cover portion radially surrounds the engagement portion. The annular cover portion rotates relative to the annular engagement portion in a second rotational direction to cause rotation of the engagement portion in the second rotational direction such that the engagement threads remain threadingly engaged with the neck threads. The annular cover portion rotates in the second rotational direction and causes rotation of the engagement portion in the second rotational direction to threadingly disengage the engagement threads from the threads when the pin is attached to the locking cap.