Apparently it's very common problem in these cars, and likely it's your problem too.
O-Ring? Isn't that what went bad in the Shuttle Challenger? Yes! The cool thing is fixing it, only cost me .90 cents. Don't go to your local autoparts store and think they'll have a o-ring in the computer for you to buy. They don't, but they do have them from a universal set in the back for around $1 a piece. Buy one and you'll solve your leaking o-ring problem in your Geo Metro.
- Parts:
-Dorman O-Ring 64213 (or 213) (Inside Dia. 15/16", Outside Dia. 1-3/16", Thickness 1/8")
-T40 Hex tool
-Assembly lube
-Parts cleaner
- How to:
1- Remove cap of distributor with a phillips head screwdriver.
2- Mark with white-out or marker the timing setting on the distributor (or have timing light to reset timing afterwards)
3- Remove the two T40 hex bolts holding the distributor in.
4- Slowly remove distributor.
5- Remove old O-ring. (It will likely break.)
6- Clean shaft with cleaner.
7- Lube shaft and new O-ring and re-install in reverse order.
8- Set timing to marks, or find diagnostics port (marked 'UP') on firewall (driver's side) and use a paper clip to disable ECU timing curve. (The pins to jump are on the tag under the hood) Then set to the proper timing. (I used 8 degrees instead of the factory 5)
Awesome! The car no longer leaks oil, and it cost me about 20 minutes and a couple dollars.
Where to find the Timing information, and which ports to jump if you need to time the ignition with a light:
And here's the old o-ring which was hardened and broke when I squeezed it: