Oil In The Spark Plug Well? and How To Fix Them?

Are you suspecting that your spark plugs are having a problem and thus you are experiencing an oil in the spark plug well? Then there are a few things you should consider before finally making a decision on what to replace and what to leave in place. Knowing the problem and how it was caused is the first step in ensuring that, the problem is sorted once and for all, and that your vehicle is safe.

In this guide, you are going to learn what oil on spark plugs is, how to sort out the problem and a step by step procedure on doing it correctly.

What Does Oil On Spark Plugs Mean?

Oil on a spark plug can be caused by several reasons such as a gasket which is failing, or an O-ring which is failing. Spark plugs are responsible to ensure that the electrical current is transmitted to the combustion chamber from the ignition system. Oil leak, which is signaled by seeing oil on a spark plug, can be able to prevent the right flow of electric current.

Spark plugs normally have shells made of metal and an electrode which is covered in porcelain to ensure that it is insulated. That means that, in case of an oil leak, it can be very dangerous.

Diagnosing The Problem Of Oil On The Spark Plug

When you encounter this problem, there are several ways in which you can sort it out. You can do it yourself without having to involve a professional mechanic. You only have to do the repair if you are sure that, there is a leakage.

What Happens When There Is An Oil On The Spark Plug?

Nothing positive. Oil on spark plug wire or oil on a spark plug can lead to several problems. It is capable of fouling the ignition coil thereby causing problems with the ignition timing.

When there is oil in a spark plug socket, there is a possibility of having misfires which in the process, will end up damaging the engine. When you see oil on a spark plug, it is an indication of an oil leak, meaning your engine is not at that moment, running at its full efficiency and thus, there is a need for service.

How A Spark Plug Works

The work of a spark plug is to ignite the fuel which is in the combustion chamber. The process of ignition happens when the spark plug which is positioned at the head of the cylinder, draws in both air and fuel.

The piston is then forced to move in the upward direction and in the process, compressing air and fuel which are drawn in by the spark plug. When forced back, the piston is able to create power for your vehicle.

If you have a care which is a four-cylinder, it will come with four spark plugs. The oil which is meant for the engine is the one leaking on your spark plugs. The use of that oil is to lubricate your engine and thus, if it is not getting onto the engine, then its main purpose is not being fulfilled.

Lubrication of the engine is very important since there is a lot of heat which the moving parts in the engine generate. The friction causes a lot of wear and tear, and thus, lubricants are very important. When you lubricate using oil, it reduces the effect of heat as well as dissipate the heat which is already generated.

What Causes Oil To Leak Into The Spark Plugs

The main cause of a visible oil on spark is a gasket which is worn out. if that is the case, there will be a need for you to replace them with new ones. Though it is going to cost you, it will be worth as it will, in the long run, help in ensuring that, you prevent further damage which might in the process, lead to big losses.

The worst scenario is where the gasket head is faulty, as it will be able to allow the oil to be able to leak without any blockage to out of your vehicle engine. This might lead to you doing an expensive repair and thus, it will be best to diagnose the problem and fix it as soon as possible before it worsens.

1. Failing Piston​

​A piston which is failing could be unable to house the compression rings at the bottom and top of the engine and thus, create room for possible leakage of oil on a spark plug. Other than that, the heat is capable of making the pistons to fail.

If the heat is in excess, the pistons develop cracks and thus, they become vulnerable to oil leakage. It is a problem which can be quite serious and which will need immediate attention once you detect it. Once there is a crack or a hole in the piston, you will need to replace it instead of repairing.

2. Leaking Valve Cover Gaskets​

​It is a cover which is made of metal and it is situated at the end of the engine to help in preventing oil from leaking into the engine. You will find the gaskets between the engine and the valve cover. It is normal for the gaskets to become faulty on a frequent basis and in the process, expose leaking oil into the engine.

High temperatures are what mostly affects the gaskets as they become brittle and start letting oil through. The leakage goes up to the spark plug and causing them to become faulty. If that happens, you will have to immediately change gasket of the valve cover .

You have to regularly check the oil level and check for potential leaks. If you happen to see dirty oil clogged filters or dirty oil, it is a sign that there is a leakage in the system. If you ignore it, it might cause you very expensive repairs.

3. Failing O-Ring Seals​

​They are seals which you will find at the spark plugs’ bottom. When they are defective, they could let oil to pass through thereby causing engine damage. If you detect that there is oil around the spark plug, especially at the bottom, you should immediately try to diagnose the problem.

If there is a misfire and oil in the spark plug well, then that is a serious problem. It could be the start of an engine misfire which in the process, could lead to serious problems. You will need to ensure that you repair or replace the O-ring seals if they are faulty.

But if this happens, you will have to change both the spark plug and the O-rings and it has to be done immediately. When you do it immediately, it will ensure that you will not need to worry about the spark plug being affected by the leakage of oil.

4. Failing Piston Compression Rings​

​This is situated at the bottom and top of the engine of the car. They are responsible for ensuring that, oil is prevented from getting into the combustion chamber. They also assist in ensuring that the excess oil on the walls of the engine cylinder is removed.

If these rings fail, it is possible for the oil to make its way past the pistons, in which event, a leak of the oil into the system will occur on spark plug wires or spark plug causing several problems.

5. Worn Valve Guides​

​The valve guides are the ones which regulate the air intake by ensuring that the valve is in place when the engine runs. If they are worn out, the only solution is to ensure that, you replace them.If you don’t replace, they will make the spark plugs to be vulnerable to leakage of oil. When the valve guides are worn out, it could lead to complicated engine issues and that is why you should replace them immediately you detect a problem with them.

Step by Step How To Fix Oil On Spark Plug

What You Require:

  • Spark socket and socket plug
  • Screwdriver
  • O-ring spark plug tube seal and valve cover gasket
  • Engine sealer
  • Pliers
  • Power handle
  • Extension and ratchet
  • Spray cleaner

Step one: Understand the gaskets

You should not overlook the gaskets just because it is a tiny item. Just know that as small as it might seem, it is very important. If you know how the engine is constructed, the gasket is meant to seal it.

The gasket is an elastic band which is attached to a component of the engine. They vary and are usually shaped into the components which it is going to seal. Examples being valve gasket, head gaskets, and cylinder gaskets.

When the gasket is faulty, it will allow fluids, including oil, to seep into wherever it wants to freely. That is why, when a valve gasket is broken, you will find the spark plug threads covered with oil.

Step Two: Remove The Spark Plug And The Valve Cover

To get to what is causing the problem, you will have to remove the valve cover as it stores the tubes of the spark plug. Before this is done, you should make sure that you have removed the spark plugs using a ratchet and a spark plug socket, one after the other.

Once all of them are removed, you will have to remove the clamp which is connecting the valve cover to a hose. You will do this through using pliers to unlock it after which, you will utilize your hands to pry the hose out.

Remove the harness which lies across the valve cover. Once you are done, use a power a socket and a power handle to unscrew the nuts which you will find on the top of the valve cover. Do the unscrewing, one after the other, until you feel it loosen and easy to remove using your fingers.

Get your flat screwdriver and stick it in the gap of the valve cover. This will help you in ensuring that you pry out the cover due to the fact that, it is normally tightly secured. After it is loose, lift it gently and set it aside.

Step Three: Seal Removal

After you are done with removing the valve cover, you will observe that in each spark plug well, there is a seal. They are the ones which have failed to protect the spark plug from the oil. To do a replacement of these is very simple to ensure you have new valve cover gasket and seals ready.

Step Four: Valve Cover Gasket Installation

You will have to start by installing gasket of the valve cover . It is uniformly shaped towards the cover and there is a need to secure it around the edges tightly. To ensure things are easier, you can add a liquid seal on its edges before you place on it the new gasket as this will prevent it from sliding. The gaskets which are durable tend to be made from high-quality silicone, go for such. If you do so, then they will not require retyping and thus, reduce a lot of work for you.

Step Five: Spark Plug Well Gasket

It is now time to place the new spark plug well gaskets. They are circular in shape and they are the ones which lie on the spark plug well rim. Just like gasket of the valve cover , you will have to add a liquid sealant to its inner circles.

After that, you will have to place it on the spark plug well and then push it tightly down. After you have secured it well in place, you can add the nuts which you previously removed. Use your hands to spin it until it sets, then gets the socket and power handle to ensure that it is locked in place.

When you are tightening the nuts, you have to ensure that you follow the right way to avoid causing any damages to the valve cover. The valves are 1, 2, 3, 4; when you are doing the tightening, do it in the order of 2-3, 1-4.

When you are through with tightening the nuts, you have to place everything back in place. Ensure the hoses are connected, the spark plug wires and the wiring harness. If you notice that your engine has a lot of splatters, you can use an oil cleanser to rinse it off.

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Benefits of oil in spark plug well?

There are a few benefits of having oil in the spark plug well. First, it helps to keep the spark plug cool, which can prolong its life. Additionally, it lubricates the spark plug and can help to reduce fouling. Lastly, it can help to improve the performance of the engine.

Factors to consider before buying oil in spark plug well?

There are a few factors to consider when purchasing oil for the spark plug well.

Size of engine

The size of the engine will determine the size of the spark plug well, so you will need to make sure that you get the correct size.

Type of oil

You will also need to decide what type of oil you want to use in the spark plug well. Some oils are better at cooling and lubricating the spark plug than others.


The price of the oil will also vary, so you will need to decide what you are willing to spend.


You will need to decide which brand of oil you want to use. Some brands are better than others at keeping the spark plug cool and lubricated.


Some brands offer warranties on their oil, so you may want to consider that when making a decision.

Customer Service

Finally, you will want to consider the customer service of the company. If you have any questions or concerns, you will want to be able to easily reach someone who can help you.

FAQs about Oil In The Spark Plug Well

1. Is it bad to have oil on the spark plug threads?

Oil in a spark plug is an indication of a serious problem which you should repair as soon as possible. If you don’t, it can lead to extensive damage to your vehicle engines such as warped or broken valves and pistons. If you don’t repair the head gasket, it can lead to the engine being destroyed completely.

2. How will I know if gasket of the valve cover is bad?

You will know by a reduction in the performance of the engine and misfires. It can even result in a fire happening under the vehicle if you don’t repair it. When the oil happens to leak from the gasket of the valve cover, it goes upto the galley of the spark plug and then goes on to leak into the tubes of the spark plug.

3. How much does it cost to replace a valve cover gasket?

The average cost of a valve cover gasket replacement is between 440 dollars and 553 dollars. The labor is between 420 dollars and 530 dollars. This does not include fees and taxes.

4. Can Oil ruin spark plug wires?

When gasket of the valve cover fails, it will make the oil of the engine to leak onto the wires of the spark plug and in the process, damage them. In the process, the entire engine is likely to misfire as a result of the spark plug wires failing.

5. What does it mean when there’s oil in my spark plug well?

It means that there’s too much oil in your engine, and it’s being deposited into the spark plug well. This can lead to poor engine performance and decreased fuel economy.

6. Why is my spark plug hole full of oil?

There are a few reasons why you might have oil in your spark plug well. One possibility is that you’re overdue for an oil change; over time, oil can build up and leak into the spark plug well. Another possibility is that there’s a problem with your engine’s seals, which is allowing oil to seep out.

7. What can I do to fix the oil in my spark plug well?

If you’re overdue for an oil change, have that done as soon as possible. If you think there may be a problem with your engine’s seals, take it in for servicing. In the meantime, try to keep as much of the oil out of the spark plug well as possible by using a funnel to add oil to your engine, and be sure to wipe up any spills.

8. How do I get oil out of my ignition coil??

If there’s oil in your engine, it will eventually find its way into the spark plug well. Over time, this can cause problems with your ignition coil, as the oil can damage the insulation and decrease the coil’s performance. If you’re experiencing these issues, you’ll need to clean out the ignition coil and replace the spark plugs.


You have to ensure that you maintain your spark plugs through avoiding oil leakages. In case there is a worn out cove gasket, replace it immediately so that, there will be no oil leakage. If you don’t prevent oil leakages, they can cause you serious engine problems.

But before you do any replacement, you have to first of all rule out that, there is no other problem. This is important due to the fact that oil leakages can be caused by various faulty components. You should be sure that what you are replacing is the culprit for the oil leakage.

You will need to give your spark plugs thorough attention just the way you do to other automobile parts. If you neglect them, it could lead to you having to replace them, a cost which you could have saved yourself had you been more careful in preventing oil spillages and leakages.

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