5 - 20 minutes
Macbook Late 2008 Aluminium was a bit too old and when I tried to run XBMC kodi and Eclipse Luna. The temperature gauge pro always pop that my CPU temperature is getting hotter. I decide to replace the heatsink and the thermal paste as well.
It did not go smooth even I had the iFixit pro tech tool kit. I think when I did the first attempt which is removing the logic board I was too excited to use the tool kit so I was really in a hurry. It happen the thing that I don't like to happen which stripping the screw :( it was a bit of a struggle but after using different type of approach of getting stripped screw out I solve it using a rotary tool kit with the help of screw extractor from Ifixit took me for about a month to solve it.
The first advice I want to give is to be patient on small screws.
Think everything is easy and entertaining and don't give up when you see struggle. I would like you to think it this way first attempt is not always good but the more you do it the more it you get the hang of it.
Pro Tech Toolkit
MacBook Unibody (A1278) Heat Sink
Arctic Silver Thermal Paste
Arctic Silver ArctiClean