I love this quote from Sheldon Brown's website. It is like he is daring you.
Servicing Freewheels
Note: I advise against doing this, because it is generally not worth the trouble. The freewheel is the least important bearing on a bicycle, since it only turns when it is not carrying any load.
Nevertheless, some people will ignore my advice and try to service freewheels, so here's how to do it: