The oil filler cap plate for the Citroën 11CV Perfo/HY manufactured up to January 1966 is a crucial component for properly sealing the oil reservoir. It ensures that oil does not escape and prevents internal contamination. This specific plate is designed to fit precisely with the car's housing, contributing to the authenticity and preservation of the vehicle. It is an essential part for collectors or restorers striving for the original state of their classic Citroën car and ensures the proper functioning of the engine by protecting the oil systems.