What Is There Oil In Spark Plug Well?

Our vehicles run because of several important components efficiently working inside them. Spark plugs are one such important component of a car that is responsible for generating the spark which ignites the fuel and air mixture in the internal combustion chamber. This spark is what is responsible for starting the car. Oil is also an important lubricant for the components of the engine while it is running. But sometimes this oil leaks into the spark plugs causing the issue, oil in spark plug well. This article discusses some causes of this issue so read on to get a better idea. 

What Causes The Issue Oil In Spark Plug Well?

There can be many reasons that cause the issue oil in spark plug well. When you have oil in spark plug well, your car will show several symptoms like weaker engine performance, blue exhaust from the tailpipe and engine misfires. If you are seeing such symptoms from your car, it is important to understand the reasons for such an issue to provide the necessary fix. 

1. Worn Valve Cover Gasket

The engine contains a metal part on top of it which is called a valve cover. A valve cover gasket sits in between the valve cover and the top of the engine cylinder head. This keeps the engine sealed well to avoid oil leaking from it. However, with time, the cover gasket will wear down due to a lot of heat from the engine. This will cause a crack in the gasket causing the oil to leak. 

How To Fix?

Simply replacing the valve cover gasket should solve the problem. If the fix is not done fast enough, the engine may suffer permanent damage due to insufficient oil. 

2. Oil Valve Guide Seals

The valve guides assist the vehicle in managing the intake of air into its engine. In simple words, the valve guide seals, secure the valve during the engine operation. These seals eventually start to wear making them brittle which results in cracks. The oil thus finds easy to leak through them causing the problem, oil in spark plug well. 

How To Fix?

It is recommended to change the valve guide seals with time as it is prone to wearing down. Such a regular replacement will prevent oil from leaking into the spark plugs. If worn valve guide seals caused oil leaks, then replacing them should solve the problem. 

3. Bad O-Rings

There are O-ring seals under the spark plug tubes. When these O-rings wears out or get damaged, the oil will leak through them causing the problem oil in spark plug well. 

How To Fix?

Such oil leaks will cause a lack of oil in the engine which is not acceptable. If this problem is ignored, it will cause irreparable damage to the engine. The oil also saturates in the spark plugs so you will need to go replace the spark plugs as well. 

4. Bad Piston

A piston can crack if it is exposed to too much heat. This will cause the piston to make knocking sounds and rattle quite a bit. A bad piston will then let oil leak through it into the spark plugs and this will cause all kinds of issues. You can identify the issue by seeing symptoms like an engine that misfires frequently and weak engine performance. These problems will ruin your car’s engine if the piston is not replaced as soon as possible. 

5. Bad Piston Rings

In your vehicle, you can find piston rings on the top and bottom of the pistons of an internal combustion engine. These piston rings are assigned to stop oil from entering the combustion chamber and remove extra oil that gets onto the cylinder wells. 

However, worn and cracked piston ring won’t be able to perform their function well. They won’t be able to stop oil from entering the spark plug wells. You can identify this issue if you see blue smoke coming from the exhaust along with the smell of engine oil coming from the cabin. 

Common Symptoms Of The Presence Of Oil In The Spark Plug Well

There are a few common symptoms that indicate the presence of leaked oil in the spark plug well. These common symptoms will help you understand that there is oil leakage and take action as soon as possible. Some of the common symptoms of oil in the spark plug wells are:

1. Gas Smell From Tailpipe

If you notice a gas smell from the tailpipe, then it may be an indication of oil leaking onto the spark plug wells. The smell in many cases may be strong enough to penetrate the car cabinet. 

2. Blue Smoke From The Exhaust

You may have seen some cars emitting blue smoke from the exhaust. This is an indication of oil leaking onto the spark plug well.

3. Decreased Engine Performance

Since the oil in the spark plug well touches the plug, it causes a decrease in the generation of spark. This spark is what is responsible for the ignition that occurs in the car. The oil contamination of the spark plug’s tip would affect the engine performance adversely. Thus a decreased engine performance will be an indication of oil in the spark plug wells.

4. Engine Misfiring

This happens due to incomplete fuel or air mixture combustion in any of the engine cylinders. With oil in the spark plug well, there are fewer chances of the plug generating spark for the complete ignition of the gas/air mixture. Hence, you would start noticing your vehicle’s engine misfiring.

5. Increased Fuel Consumption

With oil leaking into spark plug wells, your car will start consuming fuel more. So if you see such a problem, get your car checked by a mechanic to see if there is oil leaking into the spark plug wells. 


Oil leaking into the spark plug wells is quite an important issue that must be dealt with as soon as possible. Make necessary arrangements to do the repairs done as soon as you notice such an issue. Oil leaking into the spark plug can cause extensive damage to the engine, such as broken or wrapped pistons and valves. If the repair is not done in time, there will be heavy damage to the car engine’s head gasket and fatal destruction. There is also the chance of an engine fire if the spark plug ends up igniting the oil. 

Thus as soon as you suspect leaked oil in the spark plug, get your trusted mechanic to check your car. Get the parts replaced or fixed as advised by the mechanic and solve the issue to avoid any further damages.

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