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.