Oil on Sparkplug

Welcome to the forum.

Plugs, wires, and a new cam cover gasket will help out a lot. What was the exact code?

I doubt if the rings could get that bad. It is just a leaky gasket.

Most all have to do with three things.
Wiring/connection problem
O2 itself
An exhaust leak.

Remeber that 96 and newer models have two O2 sensors. One in the exhaust manifold and the other at the end of the catylitic convertor. Both can set a code. The one in the exhaust manifold provides the PCM info for adjusting the air/fuel ratio, therefore the engines performance. The one at the end of the cat is for checking on the function of the cat and the first O2.

Good luck and post back with your results. :)

How many miles on your SL2?

Ok, we know we need a cam cover gasket. The oil that leaks into the plug well can break down the insulation on the plug wires and cause misfires.

Number 1 plug is sooty and definitely running rich. Have the pulgs been replaced? How many miles ago? What type of plug. NGKs are factory. I've used AC Delcoes. Work well and are inexpensive. Stay away from platinum plugs. Expensive and don't work well with the type of ignition in Saturns.

Have the plug wires been replaced? How many miles ago? What type?

Have the O2 sensors been replaced? Both or which one? What kind? You mentioned that you were told the O2 was bad before and it was not the problem. What was the problem?

Low voltage on the front O2 sensor (PO131) indicates a lean condition. This can be caused by a vacuum leak. Check the vacuum lines for leaks, especially the PCV line and the brake booster line.
Saturns do not use Mass airflow sensors (MAF).

PO141 ididcates a heater circuit malfuntion in the rear O2. It is either in the O2 itself or the voltage supplied to the O2. The voltage being supplied to the rear O2's built in heater is either low or nonexistant. Have the voltage checked at the rear O2.

PO171 also indicates a lean condition. Again first check for vacuum leaks. Less likely is a dirty fuel filter or low fuel pressure as a cause.

Multiple misfires (PO300) most likely causes are plugs, wires, corrosion on either the coil towers and/or coil mounts, and a stuck EGR valve.

The two codes that indicate a lean condition are confusing considering the carbon covered plug and the black smoke from the tailpipe. The rich condition this indicates can ruin a catylitic convertor. The good news is "Good compression".

I would start with the most likely and least inexpensive fixes. New plugs, clean or replace wires, clean the coil towers and mounts, replace cam cover gasket, clean the EGR valve, check for proper voltage at the rear O2 wires, and check for vacuum leaks.

There should be a diagram of the vacuum lines on a sticker under the hood.

Have either of the O2s ever been changed?
If not I'd say it might be time to bite the bullet and replace them. The recommended change interval is 100,000 miles. I have 130,000 on my SC2 and have yet to change the O2. Knock on wood. A bad front O2 will cause rich running, poor gas mileage and ruin your cat. At least change the front O2. Do not use any grease on the electrical connection. Believe it or not the O2 takes in outside air thru that connection!

Could your cat be plugged again? Can be tested for with a vacuum gauge. You can also remove the front O2 sensor and see if it runs better. If it does it might be the cat.

The valve cover leak is a slow leak. The plug wells fill up with oil but it takes a while. If the plug wires are that new I'd clean them using some waterless hand cleaner and reuse them. That is unless they have a lifetime gaurantee and don't cost you anything to replace.

Have you ever cleaned the EGR valve and it's port? Have you ever cleaned the throttle body?

Get a volt meter and make sure you have 12 volts to the Rear O2's heater circuit.

Good luck and let us know what doin.