What Does Oil on a Spark Plug Mean


Last Updated on January 26, 2023 by Victor Lukasso

If you find oil on a spark plug, it typically indicates that there is a problem with the engine’s piston rings or cylinder walls. This can cause the engine to lose compression, which can in turn affect its performance and fuel efficiency.

One of the most common reasons for oil on spark plugs is worn or damaged piston rings. The piston rings are responsible for sealing the gap between the piston and the cylinder walls, and when they become worn or damaged, they can allow oil to escape into the combustion chamber. This can cause the oil to be burned along with the fuel, which can leave deposits on the spark plugs.

Another common cause of oil on spark plugs is a problem with the cylinder walls. When the cylinder walls become worn or damaged, they can also allow oil to escape into the combustion chamber. This can be due to a number of different factors, including a lack of lubrication, overheating, or the use of low-quality oil.

If you find oil on your spark plugs, it’s important to address the issue as soon as possible. Ignoring the problem can lead to further damage to the engine, including reduced performance and fuel efficiency. In severe cases, it can even cause the engine to fail completely.

Now that you’ve known what oil deposits on a spark plug means, let me show you possible ways to stop oil deposit on your spark plugs.

How to Stop Oil Deposit on Spark Plugs

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

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

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

Drain Extra Oil

If you notice oil flows into your spark plug as a result of 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.

Install new O-Rings

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

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, do well to ensure the new O-rings fit properly and their tapers are faced directly towards the engine.

Head Gasket Replacement

It’s advisable to take your vehicle to a mechanic to replace your head gasket. Also, you can decide to make the purchase and take it to an auto shop for a fix.

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Change 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.

Valve Cover Gasket Replacement

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

However, you should perform the operation with caution to avoid leaks.

Use High-Quality Oil

Repair the Cylinder Wall

That’s it.


Does Small Amount of Oil on Spark Plug Threads Matter?

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


Oil on spark plugs is a common problem that can have a number of different causes. If you find oil on your spark plugs, it’s important to address the issue as soon as possible to prevent further damage to the engine. If you