Here's a writeup on how to change the S/C oil on 96+ L67's. I wanted to make my own writeup because the writeup I saw didn't have pictures.
Parts you need:
-2 bottles of GM Supercharger Oil Update!! GM has changed the part #. Part # is now 10953513. Old number: P/N 12345982
-A 3/16 Hex bit and driver. I had to use the electric screwdriver seen in the picture to get the extra leverage I needed to break the plug loose.
-A cleaned out liquid soap bottle with pump.
-Make sure engine is cold.
-Using the 3/16 bit, remove this plug on the snout of the S/C.
-Here's the plug removed. The oil level was low. This is Typical if the S/C oil has never been changed.
-Remove the pump from the soap bottle and place the suction end of the pump into the hole. Pump the old oil into the soap bottle. The old oil will smell very bad and will be a brownish color.
-Here's the soap bottle with the oil fluid in it. FYI the new fluid is clear.
-Fill the S/C with the new oil up to the bottom of the threads on the hole. Do not overfill! It will take almost both bottles to fill the S/C. The S/C oil bottles have a suntan lotion type dispenser so a funnel isn't necessary.
-Here's the new oil in the S/C filled up to the bottom thread. It's hard to see the oil, but it's there.
-Put the plug back into the S/C. Make sure it's snug. It doesn't need to be torqued very much to seal properly.
-Wipe up the area if you had spilled any oil and clean up. You're Done.