I think, 1. Both head oil is coming to one engine oil bank. So, you can change only one head gasket, only if the head gasket is not blown internally to the oil circuit. In other words, you can change only one head gasket, if gasket has not blown internally. You should check your oil does not mixed with water. 2. It is possible that, water is coming from gasket of water pump, not head gasket. 3. You should check flexi-hoses of the water circuit. They leak usually. 4. I would check around the radiator such as Drain knob, pipe clamps etc. Sent from my iPhone using Tapatalk
