Oil In The Throttle Body – Common Causes

Oil In The Throttle Body – Common Causes

A throttle body is an essential part of the air intake system that regulates the amount of air flowing into your engine.

A fuel-injected component is situated between the air filter box and the intake manifold.

Oil in the Throttle Body Causes and Solutions

Clean air usually passes through the throttle body and is directed into the engine to aid combustion.

However, despite this free flow of air, there are some instances where you might find oil trapped on your throttle body.

Are you wondering what could be the possible reason for this? Well, there are various causes of oil in your throttle body, including excessive crankcase pressure.

To know the source of this problem, below are the top possible reasons oil is on your throttle body.

In addition, we will discuss the signs of oil in the throttle body and what you can do about it. So let’s get started.

Causes And Solutions Of Oil In The Throttle Body

Excessive Crankcase Pressure

Crankcase high pressure might be the reason why you found oil in your throttle body.

When the crankcase is subjected to excessive force, it can push the engine oil into the throttle body due to its high pressure.

Worn-out rings or worn valves may be the cause of this tension.

Moreover, there could be too much oil in the crankcase that may push excessive engine oil into your throttle body.

Therefore, these worn-out rings let combustion gasses pass through them, accelerating the crankcase pressure.

You might notice this condition with strong spikes in your crankcase pressure.

If you ever find yourself in this situation, it would be best if you check the piston rings. If they are worn out, you should replace them with new ones.

Investing in a new loop not only minimizes crankcase pressure, but it assures you that no gas will leak through them.

Excessive Miles On Your Engine

A car might have excess miles on the engine, which eventually causes blow-by (gasses passing through poorly-sealed rings).

When this condition happens, it will result in oil settling in your throttle body. Therefore, if your engine has excess blow-by, it will probably push oil in your throttle body.

Now, how can you solve this problem? You don’t have to worry because the possible solution ensures you do not run excess miles.

However, if you are already caught up in the situation, consider taking your vehicle to a mechanic to help you with the cleaning process; you might as well clear this mess using a throttle body cleaner.

Use Of Wrong Piston Rings

A piston ring is a stretchable split ring that seals between the piston and the cylinder wall.

Moreover, piston rings fill the combustion chamber to prevent the loss of gasses to the crankcase.

These rings also play a vital role in the smooth running of the engine gasses.

There are two types of piston rings you can use. These are the cast iron and molybdenum rings (mostly known as moly rings).

If you are using a cast ring, the possible reason for finding oil in the throttle is that these rings sometimes fail due to weak resistance to scuff.

Contrastingly, moly rings serve the best as they allow uniform unit wall pressure and effectively resist high pressure.

Also, these rings cannot break easily; they can help you for years without wearing off.

Moly rings can take thousands of miles without damage, so it’s a perfect choice for you as it will prevent oil from being pushed in the throttle body.

Ring Sealing Problem

A proper ring should be able to prevent oil from passing through. If the loop is not correctly sealed, it may allow oil to pass through whenever there is excess pressure.

So, the best way to control oil in the throttle is by improving how the rings are sealed.

Moreover, rings that are adequately gapped will help you prevent crankcase pressure. Oil leakage in the throttle body will also be minimal, improving its performance.

The best way to curb oil from going into the throttle body is to seek for an expert to fasten the rings for you appropriately.

Oil in the Throttle Body

Signs Of Oil In The Throttle Body

The throttle body plays a vital role in efficiently operating the engine. So, it can be easier for you to identify a problem whenever it arises while driving.

Below are the top 5 signs you should pay attention to, indicating oil in your throttle body.

Rough Engine Idle

Rough engine idle occurs when a throttle body does not function effectively.

You can notice this if there is a low idle after starting the car as the engine will be performing in a poor state.

Moreover, you might be experiencing interruptions whenever you come to a stop.

Since your vehicle engine is usually the most sensitive at idle, when the slightest change occurs, you can notice it quickly.

The combustion process will not perform well whenever there is oil, dust, or other contaminants in the throttle body.

So, if you notice your car’s engine is moving up and down and producing strange sounds, it should convince you that there is oil in the throttle body.

Check Engine Light

In most vehicles, an Electrical Throttle Control (ETC) plays a significant role in keeping track of the throttle body performance.

If the system ascertains an issue, it will signal the ETC, which sheds light on the check engine light on your dashboard.

Therefore, whenever the oil is in the throttle body, your engine light will sense it by illuminating light.

Uneven Or Slow Acceleration

As mentioned, the function of a throttle body is to regulate the air-fuel mixture that enters the engine.

So, when there is oil in the throttle body, it can tamper with the air-fuel combination. Hence, giving you a hard time when accelerating.

How can you detect if there is oil in the throttle body?

You can quickly notice this issue when your car has uneven acceleration whenever you push down the accelerator pedal.

For instance, the vehicle might move faster than usual and sometimes slow down unexpectedly.

Airflow Disruptions

A throttle body in good condition will always work effectively, and air will not be blocked.

Pressure problems often happen when there is no unrestricted airflow within the throttle body.

Oil in the throttle body is no different as it causes poor performance, especially the pressure issues in the system.

Therefore, if you notice your throttle body is stuck or not in a proper position, the chances are high that there is oil in the throttle body.

You wouldn’t want to experience more problems with your throttle body. Consider paying attention to these signs.


Misfires occur when there is incomplete combustion inside the combustion chamber. Also, when the air-fuel mixture meets the spark plug’s weak spark, it causes misfires.

However, this does not necessarily mean that the oil in the throttle is causing this problem.

Misfires in this criteria mean that the amount of air passing through the throttle body is not sufficient. The oil in the throttle body does not allow a free flow due to the blockage.

Therefore, whenever there is incomplete combustion, it causes your engine to misfire.


Oil in the throttle can be a pain, especially if you are busy and depend on your car drives daily.

While the leading cause of the problem is excessive crankcase pressure, your vehicle might start behaving abnormally.

You don’t have to worry as there are always solutions to these issues; you can handle everything with the help of the above options you’ve come across.