Why Does My Oil Smell Like Gas?

by Synthetic Oil | Last Updated: July 24, 2022

Once you have driven long enough, you start running into a bunch of puzzling issues. Although you may not immediately know the source of a problem, you know when something is wrong. One of those issues is your oil smelling like gas. Both oil and gasoline are necessary for any combustion engine to function, but they usually never mix. This is a very serious situation, one that you need to find the root cause of as soon as possible. Next time you ask, why does my oil smell like gas, you will know the answer.

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Can I Drive When My Oil Smells Like Gas?

Driving when you detect gas fumes in the air is not recommended, but it does not spell trouble right away. You still have plenty of time to reach your destination (unless you are driving thousands of miles) and diagnose the situation. Do keep in mind, though, that oil smelling like gas often means that you are burning through oil like crazy and could do significant damage to your vehicle.

Also, if you must drive a vehicle with oil smelling like gas, also known as oil dilution, you need to take precautions. First, top off your oil, if it is low. The better option is to replace the oil and oil filter. Then head over to an auto repair shop that you trust, since they will have the diagnostic tools to find the root of the issue. The sooner you get oil dilution taken care of, the better it is for your car.

What is Oil Dilution?

Also known as fuel dilution, this happens when fuel—gasoline or diesel—travels into the engine’s crankcase, eventually leading to watered-down motor oil. When this happens you may smell gasoline mixed into your car’s engine oil. Some vehicles are more prone to oil dilution than others, such as police vehicles, fire trucks, and delivery cars, due to the stop-and-go nature of their usage.

Why is gas in your oil a problem? Oil dilution causes a couple of problems:

• Less viscosity, interfering with lubrication
• Higher oil consumption
• Greater piston, piston ring, and cylinder wear
• More oxidation
• Less effective detergents and other additives

Here is a video also explaining how engine oil becomes diluted with fuel:

Symptoms of Oil Smelling Like Gas

Fortunately, fixing issues in a car is a little easier than solving health conditions in people. You can usually locate a faulty component with some investigative work. For example, if you have gas mixing with your motor oil, there are going to be a few noticeable symptoms that arise:

• Strong gasoline odor. Sometimes, fuel ends up in the crankcase, causing a strong gasoline odor to waft up through the vehicle. You will most likely notice this while driving.
• Gasoline smell on the oil dipstick. When you go to check your oil level, sniff the dipstick. If you detect the presence of fuel, it may point to fuel dripping into the oil pan.
• Excessive oil. Has your oil level increased suddenly? Unless you topped it off and forget, this is something pointing to oil dilution or some liquid entering the oil pan. Sometimes this is water, but it may also be gasoline or diesel.
• Off-color exhaust smoke. Black, white, or gray smoke—all point to issues with the engine. For example, rich running causes a thick smoke to form.

What Causes Oil to Smell Like Gas?

If your engine is suffering from oil dilution or another reason for the oil smelling like gas, you need to know where the issue lies and fix it. Some of the reasons for this problem are far more serious than others, but none of them should be ignored for too long.

Here are the causes for oil smelling like gas:

You Drive Short Distances Only

In this economy, you might think that driving your car only short distances is the way to save money and prevent any costly repairs from happening. Well, think again. With most cars, gas is running down into the oil pan, even when the engine is functioning properly. However, that gas is getting burned off and joins the fumes from the oil.

Driving short distances does not allow the engine to reach the appropriate temperature to burn off that fuel. After a while, the fuel will fill the oil pan to the point where you can smell it.

If you suspect that driving short distances is causing your oil to smell like gasoline or diesel, the first step is to change your oil and filter. Drive around again to see if you still smell the fuel. If that got rid of the problem, then you know the cause.

Driving short distances often? It’s recommended that you change your oil more often than if you were doing long drives.

Failing or Worn Piston Rings

The piston rings in your engine serve a number of purposes, but the main one is regulating the pressure of oil. Should the rings become too worn down, they could allow fuel moving through the engine to leak into the oil pan. In turn, you smell the gas fumes as they burn off. Other signs that your piston rings need to be repaired include grayish-white exhaust smoke and excess consumption of engine oil.

You can take your vehicle to a mechanic and ask for a compression test or leak-down test to test for bad piston rings. Do keep in mind that this is a laborious repair because the entire engine has to be taken apart.

Too Rich Air-Fuel Mixture

One of the main reasons your oil smells like gasoline is because the air-fuel mixture is too rich. Now, what does that mean? When the fuel is too rich for your car, the combustion chamber will not be able to ignite the fuel effectively. Since the fuel is not being properly utilized, what remains runs down through the piston rings and into the oil pan.

Sensors in the motor may also be causing your vehicle to run rich. If you have an OBD2 engine scanner, you may be able to detect any problem codes on your own. That can give you some idea about where to start with your repairs.

Faulty Fuel Injectors

Fuel injectors are little devices that give the engine fuel as needed. The fuel injectors need a solenoid to operate optimally, meaning that they also need a computer to calculate the correct amount of fuel to give to the cylinders. Solenoids are a piece of the machine and will, therefore, malfunction from time to time. For example, if a solenoid is stuck in the open position, gasoline starts to leak and mixes with oil.

Should an excessive amount of gas get free from the fuel injectors, it will eventually drip down into the oil pan.

Dirty fuel injectors can also cause other problems that lead to oil dilution, including:

• Engine misfires
• Rough idling
• Poor gas mileage
• The car fails to start
• The RPM needle moves unpredictably

Faulty Carburetor

Sure, carburetors are pretty rare in modern-day American vehicles, but there are some parts around the world where carburetors are still used. Furthermore, if you have a car that was made in 1995 or prior, it could have a carburetor in place of a fuel injection system.

For those who don’t know, a carburetor is a tube that lets air mix into fuel through valves. The carburetor can adjust the amount of air mixed into the fuel to adjust the performance of the vehicle to various driving conditions. There are two valves, one above and below a kinked section called the venturi. The choke valve at the top regulates airflow, while the second valve—the throttle—assists with dragging fuel through the pipe. When the throttle is open, more fuel and airflow through, giving the engine more energy to make the car go faster.

Although carburetors are not as advanced as fuel injectors, they can cause simial problems. Should one of the valves get stuck open, fuel can leak out in excess around the piston rings and end up in the oil pan of your vehicle.

If your carburetor has an issue, you will most likely notice black or grayish smoke that you would with malfunctioning sensors. You may also notice that your car is misfiring lately.

Old Spark Plugs

Combustion chamber problems will drag the performance of your car down. One of the reasons for those misfires is old or faulty spark plugs. Fortunately, spark plugs going bad is a common issue that you can easily check for and handle on your own.

Some tell-tale signs that your spark plugs are beginning to fail to include:

• The smell of gas in your oil
• Lack of acceleration
• Engine trouble when starting
• Rough idling
• Increased fuel consumption
• Engine knocking

See oil on your spark plug threads? That’s another problem to fix right away.

Need an Oil Change

Are you keeping up with routine oil changes for your vehicle? There are a number of reasons why you should change your oil frequently—even with full synthetic oils. Dilution is one of those issues that occur naturally over time. Pair that with short trips in your car, cold starts, and other issues, and your car could end up running rich sooner than expected.

Furthermore, older oil runs more sluggishly through the engine, which can cause combustion problems and an excess of wear and tear. If you want to keep your vehicle around (and get rid of that gasoline smell), it is recommended that you change your engine oil every 7,500-15,000 miles for a full synthetic. If you have an older vehicle with significant wear and tear, you may need to change it every 3,000-5,000 miles.

Usually, swapping out the oil for a fresh batch and changing the filter will do wonders for your car.

Sensor Problems

Faulty sensors cause a lot of issues, including rich running. Commonly, an engine that is running rich is caused by one of the several air flow sensors malfunctioning. This could include the O2 sensor, MAP sensor, coolant temperature sensor, intake air sensor, or mass airflow sensor. Each of these plays a role in the air-fuel mixture that a fuel injection system puts into the engine.

Sensors failing will result in oil that smells like gasoline, as well as black exhaust fumes. Usually, you will need to visit a trusted auto body shop to have a sensor repaired.

Can I See Gasoline Mixed Into Oil?

You might assume that you can diagnose oil dilution by looking at the engine oil. However, that is not entirely true. What you will notice is that the oil appears thin, meaning that it is more transparent than usual. The best way to tell if your engine oil is contaminated with gasoline is by touch. Diluted oil will be less slick, proving that the viscosity has been lost.

Conclusion

Why does my oil smell like gas? You should now know that it is often an issue within the engine, such as faulty fuel injectors, a bad carburetor, or something else. Although the smell of gas in your oil does not immediately mean your car is going to fall apart, it is a problem that requires swift attention, particularly if you still smell gas after an oil change.