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Oil on Spark Plug? Try these Fixes

February 21, 2024 | Victor Lukasso

Having oil on your spark plug shows that there’s probably a leakage that needs immediate attention.

Although it isn’t as harmful as the Limp Mode issue, you must address it before it escalates.

As well known, oil and lubricant are meant for the engines, pistons, and other moving parts to reduce the effect of friction.

But if you notice oil on your spark plug thread while servicing your vehicle, you shouldn’t panic, as I will offer you a solution.


What Does Oil on Spark Plug Mean?

Although oil deposits don’t just come up on your spark plugs like that, when there’s one, it implies that there must have been a breakage or leakage somewhere in the engine.

Continue reading to learn what to do if you see oil on your Spark Plug thread or tip.

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What Causes Oil on Spark Plug/Spark Plug Thread

Highlighted below are some of the significant reasons why oil will leak into your spark plugs 🔌

  1. Pouring Excess Oil
  2. Faulty O-Rings
  3. Defective Piston
  4. Bad Valve cover gasket
  5. Problematic head gasket
  6. Faulty Valve Guides

Excess oil input into your car engine will cause an overflow, likely depositing oil into your spark plug. Also, if the oil is dirty, it’ll spread dirt into the spark plug, making you experience difficulty In starting your vehicle.

Similarly, the O-rings often attached to the valve cover help prevent oil leakage into the spark plug. So, any breakage in the ring due to wear and tear will lead to the free flow of oil into the spark plugs.

Also, a cracked Piston can cause oil spillage into the spark plug when there are one or more cracks on it.

Finally, if the valves and gaskets that help in alignment and sealing break or become defective, severe leaks will eventually get to your spark plugs.

What to do if there’s oil on your Spark Plug?

If you find oil in your spark plugs, clean them to clear any dirt or debris that might affect your vehicle’s performance.

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Here’s a guide on how to clean your spark plug thread

  1. Loose and clean the Spark Plug(s)
  2. Clean the hole where the spark plug is attached with a neat cloth or a carburetor cleaner.
  3. Reinstate the cleansed spark plug(s) into its hole

Your spark plug should now have a new look and extra lifespan added to it.

However, if you notice frequent oil deposits in your spark plugs, follow the guide below to stop them permanently.

How to Stop Oil Deposit on Spark Plug Threads

The first step toward fixing oil on Spark Plug Threads is finding out the root cause of the leakage.

It could be from an over-oil filling, a defective Piston, the O-rings, or valves.

Whichever one it might be, here are some fixes you might try to stop oil deposits on the Spark Plug.

1. Drain Extra Oil

If you notice oil flows into your spark plug due to excess input of oil, then you can go ahead to drain some amount by opening the drain plug.

This will allow excess oil to flow out of the engine. Alternatively, you can use an oil extraction pump for this purpose.

2. Install new O-Rings

If any of the O-rings on your valve cover has worn out, you should consider getting a replacement as soon as possible.

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You can now proceed to install the new O-rings by removing the valve cover, removing the previous rings, and installing oiled O-rings as a replacement.

Also, ensure the new O-rings fit correctly, and their tapers are directed toward the engine.

3. Head Gasket Replacement

Taking your vehicle to a mechanic to replace your head gasket is advisable. Also, you can purchase it and take it to an auto shop for a fix.

4. Change the Defective Piston

Also, this will require the attention of a professional automotive engineer. Kindly take your car to your mechanic shop and ask them to change your Poston.

5. Valve Cover Gasket Replacement

You can purchase a new Valve cover gasket in any auto aftermarket nearby and initiate a replacement yourself.

However, it would be best to operate cautiously to avoid leaks.

That’s it.

Does Small Amount of Oil on Spark Plug Threads Matter?

No, you don’t have to worry about it, but too much oil in your spark plug might introduce debris and dirt, which isn’t healthy for your vehicle.


We’ve discussed possible reasons why there could be oil deposits in your spark plug with its corresponding solutions.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.