Informational Guide

Why Does My Oil Smell Like Gas?

We discuss why your engine oil smells like gas along with some of the most common causes & fixes.

Your car requires both gas and oil to run properly. However, if you notice the oil smells like gas, you might have a problem. Why does my oil smell like gas?

In this guide, we will discuss why engine oil smells like gas and some of the main fuel in oil causes. If you don’t take care of the fuel in oil problem, it will lead to severe engine damage.

Some people claim that synthetic oil smells like gas, but that’s not typically true. So, why does my oil smell like gas in my car? Here are a few of the reasons you might end up with gas mixing with oil in car models.

Too rich air-fuel mixture

This is the most common reason you might notice a gasoline smell in oil. When the fuel mixture becomes rich, the combustion chamber doesn’t ignite all of the fuel, leaving behind some that runs down the piston rings.

Engine misfire

When the air-fuel mixture doesn’t combust properly, it can cause a misfire. When gas ends up on the cylinder walls, it causes lower compression and additional blow-by to pass the piston rings.

Failing fuel injector

Newer vehicles are equipped with a fuel injector that is mechanical. If the solenoid on the fuel injector gets stuck, gas can make its way into the crankcase and cylinders, thereby mixing with the oil.

Bad carburetor or settings

Older cars are equipped with carburetors which run with the help of a diaphragm. If the float gets stuck or the settings are wrong, too much fuel can be added to the combustion chamber, leaving fuel to escape into the system.

Faulty piston rings

When the piston rings go bad, additional fuel can make its way into the combustion chamber. This isn’t a simple solution and might require a complete engine rebuild.

Not had an oil change for a while

Not performing regular automotive tune-ups can cause dirty oil made worse from blow-by gases. If you wonder why my oil smells like gas, this could be one easy situation to remedy.

Why Does My Oil Smell Like Gas

What Are the Signs of Oil & Gas Mixing?

Obviously, when your car oil smells like gas, it’s a symptom that something is wrong. However, there are other symptoms to consider with your car or when boat oil smells like gas.

  • High oil level 
    For the most part, your oil level should never rise but usually stays the same. If it does rise unexpectedly, it could be caused by extra fluid, such as fuel or water, in the oil.
  • Strong gas smell from engine 
    If fuel makes its way to the crankcase in excess, you might smell additional gas. Sometimes, the smell is faint, while in others, it can be overpowering.
  • Dipstick smells of gas 
    If your oil dipstick smells like gas, it’s probably that fuel has mixed with the oil. This is a great way to determine if motor oil smells like gas on a motorcycle too.
  • White exhaust smoke 
    When there are issues in the combustion chamber, one of the first symptoms is white smoke coming from the exhaust. Often, this is a result of rich fuel ratios.
Engine Oil Smells Like Gas

First Things to Check When You Notice Gas Smell In Your Oil

Why does my engine oil smell like gas? We’ve discussed some of the reasons; now, let’s look at what to check if you notice the putrid smell. You can check these when your car or dirt bike oil smells like gas.

Check mechanical fuel pumps

The fuel pump is responsible for moving gas into the combustion chamber. If a fuel pump is faulty, it can lead to a rich mixture, leaving behind a gas smell. You can check the integrity of the fuel pump by using a pressure gauge.

Check spark plugs

The spark plugs are required to ignite the air-fuel ratio in the combustion chamber. Over time, spark plugs can foul out or become contaminated, thereby causing an imbalance of the mixture. Learning how to change spark plugs can help you avoid this problem in the future.

Check for a badly adjusted carburetor

Whether you need to diagnose carburetor problems in your motorcycle or car, it’s simple to check the adjustments. You can determine if the carburetor is causing the system to run rich, too lean, or it just needs some simple adjustments. This also works if your riding lawn mower oil smells like gas.

Check for low compression

Testing engine compression is essential if you notice gas in the oil. With a simple gauge, you can quickly determine the source of the problem and hopefully fix it before you end up with more costly repairs. If you aren’t sure how to check for engine compression, take your vehicle to a qualified mechanic.

Check for a blown head gasket

When your car has a blown head gasket, oil and coolant can come in contact with one another. This often leads to a sweet smell, but some people could mistake it for a gasoline smell if they had never smelled coolant before. If you notice any strange fluid in the oil, it’s best to have it looked at.

Quick Fixes When Oil Smells Like Gas: Tips from a Mechanic

What does it mean when your oil smells like gas? Hopefully, it just means that your car needs an oil change. If that’s the case, grab your oil drain pan and get the fluids replaced. Don’t forget to also change the oil filter. Even if you are working with other vehicles, it’s essential to change the oil.

For example, if you notice the lawn mower oil smells like gas or the motorcycle oil smells like gas, a simple change might be all that is needed. Learning how to change motorcycle oil is as simple or easier than working on your car.

Aside from this simple fix, most other problems will require the help of a mechanic. There’s no reason to neglect your engine. If you notice gas in the oil, have it looked at right away before more serious issues occur.

What Does It Mean When Your Oil Smells Like Gas

People Also Ask (FAQs)

Is it dangerous if my car smells like gas?

You should never ignore the smell of gasoline in or around your vehicle. Fuel is flammable, and a car fire could occur if you don't have it looked at right away.

How does fuel get into the crankcase?

Crankcase dilution happens when the fuel in the engine moves into the oil past the piston rings or because of blow-by gases that infiltrate the crankcase from normal engine operation.

How much does it cost to fix a gas leak in your car?

It depends on what the problem is. Some fixes are minor and will cost you less than $100 in parts, especially if you can perform the task on your own. However, if you are looking at major engine repair, you might be better off getting a new vehicle.

Will a gas leak cause a check engine light?

It could. Any time that the fuel-air ratio is off, it can send an alert to the onboard computer, which will cause an error code. You can use an OBDII scanner to read the code and resolve the problem.

Will gas evaporate out of oil?

While gas does not easily separate from oil, it can evaporate out of the oil over time. When it evaporates, it is drawn back to the intake with the PCV system.


Why does my oil smell like gas? We have looked at many of the top causes and given you some possible solutions to fix the problem. If you smell gas in your oil, make sure you have it checked out before larger problems occur.