The only thing you need to do to oil the A-5 is remove the tank, put a few drops in the gun there, screw the tank back on, and fire 5-10 times. Spyders can be oiled the same way.
If you want to take it apart to clean it, it's a little more involved: You'd be best opening up the manual (download it if you've lost it) and following along, but here's the basics:
1. Remove the air tank
2. Make sure the gun is uncocked (bolt forward) by pulling the trigger
3. Put your hand over the back cap and pull out the back two quick-strip pins (one goes through the gripframe)
4. Remove the back cap, spring guide, and mainspring
5. Pull out the quick-strip pin next to the tombstone (where the gas line goes into the gun)
6. Push the release lever and pull out the tombstone
7. Carefully tip the gun backward. The hammer (heavy silver bit), powertube (long black bit), bolt (short black bit), and link rod (long silver rod) will come out
8. Clean
To reassemble:
1. Slide the bolt back onto the powertube and set the hammer behind it
2. Put the link rod into the hole in the hammer and the bolt. Make sure the hole for the tombstone in the powertube is down, and the link rod is on top
3. This is tricky... Slide the whole thing into the gun. It's easier if you hold the gun upside-down
4. Put the tombstone back in, and make sure it clicks into place past the lever. Put the tombstone quick-strip pin in
5. Put the mainspring, the spring guide, and the back cap on (in that order). Put the quick-strip pins back in
6. **** it and pull the trigger. If it makes the familiar CLACK sound, you're in business!
... But seriously, just download the manual.