Hi people I have what look's to be oil in the radiator mixed with the coolant which forms a brown colour.It's not the head gasket did a check and not drinking oil and did a pressure cooling test and all is fine. Temperature sit's on normal.Somebody told me could be transmissin fluid as it passes through the radiator.I dont know if he was talking about the trans cooler etc,but he said a part in the radiator is gone so need a reco radiator.He also said it is common on Vy model.Thoughts ???.