Posted on here a last week regarding a water problem with my z , since then have had the rad. replaced, new top hose and rear coolant pipe replaced. Took the car for a run yesterday and noticed , on return that the coolant level had dropped a little, so topped it up, noticed this morning that the level had gone down, very slightly,again. Car is back in garage , they have pressure tested and say pressure is dropping slightly but dont know why.This is now starting to annoy me as everytime i take the car out I worry about it running hot, this is the second z I have owned and both have caused me the same aggro. The garage is now saying it may be a faulty thermostat but wouldnt have thought that would cause a water loss, dont want to pay for something else that may not solve the problem, any ideas ?