You should install a new retaining ring into each quick connector fitting, rotate the retaining ring around the connector, ensure the 3 retaining ring ears can be seen from the inside of the connector and the retaining ring can move freely in the slots, install the
Engine Oil Cooler line into the quick connector fitting, snap the plastic cap onto the quick connect fitting, ensure that the plastic cap is fully seated against the fitting, ensure that no gap is present between the cap and the fitting and then inspect and fill the engine oil to the proper level.