You could look for something known as Arctic Silver 5. But for overheating, you may want to look at the fan speeds of the processor as well and make sure its running at the correct speed. Try cleaning the fan. Arctic Silver 5, is very well known. I am not sure if you will get it here. But you do get other heat sink pastes.I had bought a small can/bottle of silica gel/heat sink paste compound a long time ago. Dont remember where.
Satish