pics of worn drivetrains ?
 

how am i supposed to know when my freewheel and chainring are worn beyond usable condition? In understand chain condition can be assessed by overall stretch, does anyone have any examples or rules of thumb for when gear type parts are done?

this should help

http://sheldonbrown.com/chains.html#wear

Keep changing your chain when 12 links >12 1/16". As long as your DT runs smoothly with a new chain, your DT is fine. When you put a new chain on a worn out DT, you'll know.

Just keep tensioning out the slack until it doesn't run smoothly anymore.
If you start out with everything precisely aligned then you have a ton of room for error (derailleur setups run fine with literally inches of play).

The teeth on the chainring and cog look like shark fins. Google image search yielded
http://easilier.com/Images//WornChainring.jpg

In this image you will notice the black dotted lines that show where the teeth used to be.

Don't oil your chain, man.

Ha....here we go again...

Jeebus Cripes this guy must be posting drunk or something. The amount of error perpetrated in those two sentences makes my head hurt.