A couple months back we received a donated tool
that none of us had ever seen -- one that injects grease into a freewheel without requiring you to take it apart. It fits on most freewheels, and is great for those bikes that are old or have been left out in the elements -- really handy in a shop like ours.
Here's how it works --
1. Remove the freewheel from the hub, and clean it with simple green and a rag or brush
2. Thread the injector onto the freewheel
3. Load the grease gun with grease (using a tube rather than a tub really makes this step easier!)
4. Attach the grease gun to the injector, and push the plunger down
5. When grease starts coming out the other side, you're done!
6. Rethread onto your hub, and enjoy the awe-inspiring silence of your freshly greased freewheel!