5 Causes and 7 Symptoms of Oil in the Spark Plug Well

5 Causes and 7 Symptoms of Oil in the Spark Plug Well

When it comes to the ignition of petrol-powered vehicles, spark plugs are critical. Oil which serves as a lubricant, is required for the smooth operation of the vehicle's moving parts. In fact, a lack of oil can cause severe friction and, overheating of the engine.

There should be no leaks that allow oil to seep through the plug well, as this can impair the vehicle's performance, and you should seek immediate advice from a car mechanic during a car service in Reading.

What Are the Causes of Oil in Spark Plugs?

When your spark plug is in good condition, your car's ignition should function normally, and you should have no issues. But what if you find oil on the spark plugs bottom? This issue is caused by two separate systems:

1.     The spark plug system

2.     The lubrication system

Because the spark plug ignites energy in the combustion chamber, which contains the fuel/air mixture, both are beneficial to the engine. Oil, on the other hand, works well for the engine's moving parts, reducing friction between them.

The oil is stored in the oil pan, which has a capacity of six litres. The oil is moved by the oil pump and makes its way down to the oil filter before reaching other parts.

The oil should not come into contact with the spark plug or enter the spark plug well, as this can lead to serious problems. If this occurs, it is recommended that you search online for full car service near me and request that a car mechanic can fix the problem as soon as possible. The following are the five major reasons why oil is discovered in spark plug wells:

1.     Worn Out Valve Cover Gasket

When you look at your car's engine, you'll notice a metal cover on the engine known as the "valve cover." This seal is designed to keep leaks from the vehicle's engine at bay. Nonetheless, there are gaskets between the valve cover and the engine, and they eventually fail.  This type of failure becomes more pronounced as the engine temperature rises, and the valve cover gasket becomes brittle. As a result, you may soon notice some leaks allowing oil into the spark plug well.

2.     Faulty O-Rings

If you've ever handled spark plugs, you've probably noticed the O-ring seals beneath the spark plug tubes. These seals effectively serve as a cover for the spark plug well. Nonetheless, they deteriorate over time, and if damaged, oil can leak into the spark plug well. As a result, immediate action is required to avoid further complications. Please keep in mind that the current spark plug will need to be replaced as well because the oil will saturate it and render it unsuitable.

3.     Failed Piston Compression Rings

Piston rings, which are located above and beneath the piston, keep oil from entering the combustion chambers of the car. These rings are also crucial in removing excess oil from the cylinder walls. With worn-out piston compression rings, they can rarely prevent oil from flowing towards your spark plugs. The engine oil odour would be detectable throughout the cabin in this case. You'd notice blue exhaust from the car every day.

4.     Faulty Piston

Aside from allowing engine oil to flow into the cylinder and saturate the spark plug due to a faulty piston ring, a bad piston can also cause oil to accumulate in the spark plug well. As a result of the excessive heat, the piston may crack. While driving, a faulty piston can cause engine misfire, excessive oil combustion, and rattling noises. You should not ignore such a problem and should resolve it as soon as possible to improve the performance of your engine.

5.     Aged Valve Guide Seals

The valve guides help with the intake of air into the car's engine, and they secure the valves while doing so. The valve guide seals are effective, but they can wear out over time. You will need to replace them at some point during your full car service near me because they prevent oil from reaching the spark plug well. If you don't, you could have serious problems as oil shouldn't get to the spark plugs.

Oil in the Spark Plug Well Symptoms

The number of symptoms indicate that there is oil in your vehicle's spark plug well. With these common signs, you can easily detect and resolve such a problem before the car develops further issues. These signs are useful when determining how to remove oil from the spark plug well. Some of the most common symptoms of oil in spark plug wells are as follows:

1.     The Smell of Gas Emanating from the Tailpipe

Have you ever wondered why you keep smelling gas coming from the exhaust pipe of your car? This could indicate that there is oil in your Toyota Camry's spark plug well. This is true for many other vehicles, and in some cases, the odour penetrates the car cabinet.

2.     Blue Exhaust Smoke

The exhaust pipe may soon begin to emit blue smoke, indicating that oil is being burned somewhere in the engine. Typically, such indicators appear when there is oil in the spark plug well. When there is oil on the spark plug, it affects the engine's efficiency and how it burns fuel. The fuel supply increases as the ECU attempts to adjust the fuel ratio. Regardless, unburned excess fuel in the combustion chamber would pass through the exhaust valve.

3.     Reduced Engine Performance

As the oil in the spark plug well makes contact with the plug, spark generation is reduced. Remember that this spark is in charge of the car's ignition. The oil contamination of the spark plug tip would be disastrous. In essence, the fuel/air mixture would have fewer chances of igniting in the combustion chamber of the vehicle. There will be insufficient pressure for the engine to function properly if there is no proper combustion.

4.     Engine Misfiring

Engine misfiring can occur in any of the engine's cylinders due to incomplete fuel/air mixture combustion. With oil in the spark plug well, the plug is less likely to generate enough spark to complete the ignition of the gas/air mixture. As a result, you will begin to notice misfiring in your vehicle's engine.

5.     Increased Fuel Consumption

An increase in fuel consumption indicates that the spark plug is being clogged by oil. In essence, if you notice an increase in fuel consumption, inspect the spark plug to see if it has any oil on it. This sign will show you how to drain the oil from the spark plug well.

6.     Engine Backfiring

This occurs when the fuel/air mixture combusts outside the combustion chamber of the engine cylinder. When there is oil in the spark plug well, this symptom appears. It is caused by improper combustion of the fuel particles, which causes them to migrate to the exhaust.


Spark plugs are necessary for petrol-powered vehicles because they aid in engine ignition. As a result, the spark plug must be in good working order for the engine to run smoothly. Spark plug issues would have a negative impact on the engine, and you might notice that the car starts but does not stay running.

If there was oil in the spark plug well, there would be less spark generation for ignition. As a result, cleaning the spark plug hole, replacing the spark plugs, and replacing the O-ring seals may appear critical. Continue reading to find out more about the causes and symptoms of oil on the spark plug.

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