. Well having just paid to have my head rebuilt after blowing the head gasket. A deep knocking noise was occuring and yes wait for it........ We have low fat mayonaise coloured slime in the oil. Now the car hasnt been ragged since having it back, and when I did get it back the plank who fixed it overfilled the expansion tank on the coolant so it burst out tank. Is this what probably caused it?? Now my engine runs way too hot as normal, so is it worth having these items put on??? Low temp thermostat, low temp fan switch, exhaust heat sheild? anything else? like a performance gasket?? cheers.