Hi, i,ve got a galaxy 1.9td 2001 and have the what seems to be common problem with the water boiling up within the expansion tank!! the dash is asking me to STOP, the temp guage is sitting at 90 and the water is disappearing from the tank, i've done a block test so it not the head gasket, i've put a new stat in but still doing it, i'm now gonna put a new cap and water pump on, what ANTI-FREEZE should i be using because i believe a mixture of different fluids can cause them to congeal!!!!! the expansion tank is also full of very clean and very fine bubbles not the usual snot, i'm thinking maybe the water pump has plastic impeller not working properly?!?!?! please help as the end of my tether is nigh...