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Why There Is Oil on Spark Plugs? Causes and Solutions 

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While spark plugs are very small electrical components in your combustion system, they have a major role in igniting the air fuel mixture and generating the first spark. Your vehicle must always have spark plugs in great condition to run smoothly and start properly. Many people complained about having oil making its way to the spark plugs, and the question always remains why there is oil on spark plugs?

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Your vehicle's oil is every common liquid, and it's mostly used to lubricate different engine components and prevent engine overheating due to friction. 

While it's great to have the required amount of oil in your vehicle, oil must flow through certain tubes and locations and not leaking anywhere else. One of the most important places you don’t want oil to leak into is the spark plug.

When oil leaks into the spark plug, the problem is associated with either the spark plug system or the lubrication system. Before understanding the different reasons for an oil leak to the spark system, it's important to understand how both systems work.

Many different reasons are causing the oil to get to the spark plugs. This article helps you understand the main causes of oil leaking into spark are plugs and what you should do to resolve the problem.  

What is the spark plug, and what does it do? 


The spark plug is a small electrical device that is connected to your engine cylinder. The device is responsible for providing the required spark at the right time when the engine needs it.

With this spark, the engine can generate an explosion and firing the air-fuel mixture. This spark must be provided at a specific time and with a certain frequency. Any problem with a spark plug can result in issues with the timing or the frequency of this spark.

There are two types of engine coolant a compression ignition engine and a spark ignition engine when it comes to the spark plugs.

The compression ignition engine first compresses the air before providing the required spark. On the other hand, the spark-ignition engine requires a specific spark from the spark plug to get started. In other words, the spark-ignition engine does not need any compression to get the engine firing. 

What is the lubrication system? 


Your engine's oil is one of the very important liquids required for proper engine function. This oil is responsible for lubricating the engine's moving parts and preventing any overheat due to friction. As these moving parts inside the engine get in touch with each other, they can generate much heat due to friction, and this heat can cause complete engine failure.

The oil of the engine is usually stored in the oil pan. This oil pan can fit up to 6 quarts of engine oil as you fired the engine, the oil pump, since a certain amount of oil through the pickup tube. Once the oil is sent, it has to pass through a certain oil filter to remove any dirt or debris from it before getting inside the engine. 

From the oil pan to the engine, there are many potential ways for the oil to leak inside the cylinders and make its way to the spark plug. 

Why is there oil on spark plugs? 

You probably are dealing with some symptoms confirming oil in the spark plug. Many different reasons are forcing the oil to leak and make its way to the spark plug, including

  • A bad or worn-out valve cover in the gasket 


The head gasket is responsible for sealing the cylinder and preventing any fluids from making their way from the engine into the cylinders. If the gasket valve had an issue, the oil can easily leak and get inside the cylinder and, therefore, to the spark plug.

The head gasket valve is not designed to last forever and overtime views, and because of the different extreme temperatures this part faces, it's very common for the valve of the head gasket to worn out. Then, you will start noticing some oil in the spark plug. 

If that's the case, your best solution is to take your vehicle to a professional mechanic and inspected it to confirm the head gasket problems. If the professional mechanic confirmed it's the head gasket, you must replace it with a new one to resolve the problem. If you ignored issues with the head gasket, you could introduce complicated problems requiring much money and effort to resolve the problem. Thus, you'd better take care of the problem as soon as possible. 

  • Worn out valve guide seals 


In your engine, there are some valves called the valve guides. These valve guides are responsible for ensuring that the air intake is closed when the Angel is running.


Overtime of use in like any other vehicle components, the valve guides can also wear out, resulting in insecure or unsealed valve intakes. If the valve guide wears out, it's very likely for the oil to leak inside the cylinders and make its way to the spark plug. 

If that's the case, you need to replace the valve guides as soon as possible to prevent dealing with complicated problems that might need more time and more effort. 

  • Issues with the O-ring 

The spark plug has another important piece under it to ensure fold sealing. This piece is called the O-ring. Overtime views, the O-ring can also get worse and require replacement. If the O-ring where is out, oil can also make its way to the spark plug area, and you must get it replaced as soon as possible. 

In most cases, if the O-ring wears out and requires replacements, professional mechanics will ask you to replace the entire spark plug as well.  

  • Problems with the piston 


The moving parts in your engine are called the piston. This piston is responsible for converting the energy into movement and provide the power that makes your vehicle move.

Any problems with the pistol and can also result in oil leaking to the spark plug.

If your professional mechanic confirmed that the piston has a problem, you'd better get it replaced or repaired as soon as possible to help prevent oil from leaking to the spark plug. 

One of the fastest ways to confirm your vehicles is to monitor your car's overall performance. Usually, a bad piston would result in a frequent misfire, and you will notice a significant reduction in your engine's overall performance. 

  • Faulty piston rings 


Around the piston, there are rings responsible for preventing any oil from making its way into the combustion system while the engine is operating. These rings are also responsible for removing any excess oil from the cylinders.

Piston rings can also wear out and stop doing their job. With the extra oil in the cylinders, it's very easy for this oil to leak inside the spark plugs. 

Symptoms of oil on spark plugs 


As we mentioned before, it's important to prevent any oil from making its way to the spark plug to ensure your engine's proper functionality.

It's important to familiarize yourself with the different symptoms indicating that some oil made its way to the spark plug. Luckily, these symptoms are very common, and you can easily diagnose and monitor some of them.

Here are some of the common symptoms of oil on spark plugs: 

  • You will start seeing some Blue smoke coming out of the tailpipe 


If you noticed some blue smoke coming out of the exhaust system's tailpipe, you are in a difficult situation.

When the blue smoke comes out of the tailpipe, this indicates many oil leaking to the spark plug, and your engine is in a very bad situation.

In that case, you must consult a professional mechanic and make sure that your vehicle gets the most and repaired as soon as possible.

Blue smoke coming out of the exhaust system is not a problem that you can ignore or leave for a couple of days to prevent any expensive repairs that could result in complete engine failure. 

  • A gas smell might, of the exhaust system 


When the oil makes its way to the spark plugs, the air-fuel mixture can be affected, and you will start smelling some gas smell coming out of the exhaust system.

While this problem might be associated with other exhaust systems, one of the common causes of oil leaking to the spark plugs, to confirm the culprits, you might need to consult your professional mechanic as soon as possible and ask him to diagnose and repair the problem.

Again, the gas smell coming out of the exhaust system is not a problem that you can't ignore and leave for a long time.

The problem will not prevent you from driving your vehicle. However, it would help if you took care of it as soon as possible. 

  • You will notice a significant drop in the fuel economy 


When there's oil leaking to the spark plugs, this part will not function properly, and it will not generate the required spark at the right time for the engine to start the explosion.

As a result, your engine will request additional fuel thinking that there is insufficient fuel in the cylinder, and therefore, you will notice a significant drop in your fuel economy. You will notice that more by regular visits to the gas stations more than before. 

  • Your engine's performance will drop significantly 


Your engine is expecting a spark at a certain timing with a certain frequency. If the spark plug fails to provide the spark, the engine will not generate the required heat at the right time.

As a result, you will notice that the engine's performance is different, and it's dropping significantly by the time you leave the problem longer.

If you would like to get your engine's performance back, you must take care of the problem as soon as possible. Not only will you improve the engine, but also you will save it from complete failure. 

How much does it cost to repair oil on spark plug issues? 


Answering this question depends heavily on the root of the problem. As you notice before, the spark plug's oil leaking can be due to two different reasons, including issues with the piston, the O-ring, the head gasket, or their spark plug itself.

If you are looking for replacing the spark plug only, the piece is very cheap, and it will cost you between $16 to $100. This, however, does not include labor costs, which could cost you between $40 to $150 depending on the place that you would get the job done at.

However, if the problem is not associated with the spark plug itself, repair costs can be significantly higher if, for example, you are looking to replace the head gasket itself or maybe the piston. 

For example, if you are unlucky and your problem is his gasket, you might need to pay between $1000 to $2000 on parts only.

On the other hand, if your problem is associated with the vehicle's pistons, you might need to pay between $1500 and $2500.

As you might notice, repair costs can vary significantly depending on the root of the problem, and the best way for you to confirm the final price is to consult a professional mechanic. Your professional mechanic has many tools that enable him to identify and pinpoint the culprit using some machines like the OBD2 tool. 


These spark plugs are very important components in your engine, and even they are very small. They're responsible for creating the required spark to start the fuel-air mixture ignition. Without a perfectly running spark plug, your engine will not perform properly, and it will notice a significant drop in the fuel economy.

Sometimes, it's very common for the engine's oil to leak inside the spark plug affecting its performance and probably causing complete spark plug failure. If you notice any oil leaking symptoms to the spark plug, you must take care of the problem as soon as possible to prevent dealing with significant problems in the future that requires much time and effort if not so much money. 

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