I have a 2008 Sportswagon. Overheated a few months back driving from Toowoomba back to Brisbane a few months back. Stopped and added water after it cooled down and took it to radiator bloke who fixed it, replaced the water pump. A few weeks later started to use a lot of coolant again. Took it back and did pressure test no external leakage. My concern it is internal with damage caused to gasket and at worse head. Oil is clear, and clean no oil present in coolant, not bubbling, no visible smoke and the engine sounds ok. Any advice please as to what to do next?