Friend I tell you something the oil in the refrigeration circuit is usually the problem of the button of the cylinder head, but if your vehicle has the same force as the problem, the problem can be filled in another place, check this where the oil filter is a heat exchanger, bring two hoses one enter the other, you have a bridge and close the circuit without going through the heat exchanger to put on the heat exchanger. I need that system, change the water and test, I have done it Barias Beses and that fault is very common in Renault Peugeot and Citroen do not worry until you perform the test if everything goes well just leave it like this there is not to change the piece. Good luck and let us know