Discard the retaining ring.
Important: 
   •  Do not reuse any of the existing oil lines or oil line fittings if there is excessive corrosion.    •  Do not reuse any of the existing retaining rings that were removed from the existing quick connect fittings. All retaining rings being installed must be new.    •  Ensure the following procedures are performed when installing the new retaining rings onto the fittings.