my question is , how reliable is the gauge? just supposing the water level in header tank that feeds the turbo drops, does the temperature go up on gauge? to say something isnt rite, as my guage reads just before middle point once hot. or put it another way, if it reads as i describe does this mean the engine is in no danger of damage ( overheating ) but turbo could be destroyed under boost- low headertank level. ????

 

Very inaccurate: mine doesn't even start to move until my Defi gauge hits 65 degrees.