If you perceive a gas smell in oil, you will most likely have a gas-oil mixture. Gas and oil are the primary fluids in a car that ensures the smooth running of your vehicle. When you notice oil smells like gas, you should not take it lightly because there are consequences.
You need to understand the symptoms of gas in engine oil and the leading causes to enable you to solve these issues and also prevent future problems. The cause of a gas-oil mixture can be due to faulty engine components or driving short distances at all times.
In this article, we’ll explain what causes oil-gas mixture, common symptoms of oil and gas mixture, what will happen if oil gets into the oil pan and how to fix oil smelling like gas.
How Does Gas Get Into Oil?
Blowby
The most common way for gasoline to get into oil is around the pistons that affect an engine’s combustion cycle.
Pistons are meant to fit smoothly inside a valve, with the lubricating oil in the crankcase space below and the gasoline-fueled combustion happening in the space above.
However, pistons don’t completely fill the valves, allowing the pressurized gasoline to sneak by and enter the crankcase oil.
This is called blowby, and is generally not a problem because it’s a very small amount of fuel, and as the engine heats up, the gasoline burns off.
Fuel Pressure Regulator
This device ensures the appropriate pressure for fuel moving from the tank to the fuel injectors and back to the tank. There are many parts within the regulator that can go bad or get jostled out of place, including small springs.
If other tests do not show an obvious culprit for the gasoline getting in the oil, have the regulator checked.
If the regulator has failed there will probably be other symptoms as well, such as poor gas mileage, rough idle, weak acceleration, and a check engine light illuminated on the dashboard.
Leaking Fuel Injectors
If an injector is bad it will leak fuel, compromising the fuel pressure regulator’s job. Remove injectors and have them checked. If they smell like gasoline when removed, it’s likely they need replacement.
When the injectors are removed, do a compression test to ensure that the engine is capable of holding an appropriate amount of pressure. If not, the engine will not fire as needed to run properly.
Leaking Rings
Rings are the part of the piston that fits snugly inside the valve. Too much torque or wear can cause rings to become bent, allowing gasoline to flow by in larger than normal “blowby” quantities. Rings can be fixed, but it’s a big job.
The Role of Sensors in the Fuel System
Sensors are increasingly important components of modern car engines. These are small gauges that report to the onboard computer to maintain the proper settings for various engine functions.
When sensors malfunction, you should get a warning light on your dashboard. Sensors that impact the flow of gasoline include:
- Fuel pressure sensor: This is part of the fuel injection system and is usually located on the bar with the fuel injectors. It ensures that the gasoline going to the injectors is calibrated accurately and that the fuel pressure regulator is working properly.
- O2 sensor: Located in several places, including near the catalytic converter and in the tailpipe, these oxygen sensors detect the presence of oxygen and can tell if the fuel-oxygen mixture in the engine is off. If there’s too much fuel flowing to the spark plugs, some may get pushed past the pistons and into the crankcase oil.
- Air intake sensor: These are located in the air intake on the top of the engine (not all vehicles have them). This sensor reads the air temperature to ensure the right mix of fuel and oxygen for the engine. Colder air is denser.
- Coolant temperature sensor: If you do a lot of short trips and your engine never gets hot, this sensor is more prone to failure. It tells the engine how much fuel to add to the combustion mixture (with oxygen). A cold engine needs more fuel, which can result in too much pressure on one side of the pistons if the sensor is failing.
- Fuel temperature sensor: This is located on the fuel pump, and further refines the process of fuel-oxygen delivery to the engine.
What causes oil to smell like gas?
Knowing why your engine oil has a strong gas smell will efficiently enable you to prevent gas-oil odor and fix it if the gas has already found its way to the crankcase.
#1. Short Distance Drive.
if you don’t usually drive long-distance, like driving interstates, you’re most likely to perceive gas smell.
When you drive a long distance, the oil pan will heat up to a certain degree and provide heat that will vaporize the small amount of gas that finds its way to the crankcase.
On the other hand, driving short distances will not allow the crankcase to heat up to the state of vaporizing the excess gas in the crankcase.
If most of your driving is within the city, then you have to be driving long distances. If driving long distances is out of your schedule, you have to consider changing your engine oil more often.
#2. Faulty Fuel injectors.
When it comes to the air-fuel mixture, the fuel injectors play a significant role. The fuel injectors send the right amount of fuel-air mixture to the cylinder walls that the combustion chamber requires.
Fuel injectors have a built-in solenoid that is controlled by your car’s computer. The car’s computer will send the calculated amount of fuel needed by the engine to your fuel injectors.
If you have a faulty fuel injector, it’ll spray an excessive amount of fuel to the cylinder walls, which will eventually find its way to the crankcase and cause the gas-oil smell.
#3. Faulty Piston Rings.
The Piston rings work as a sealing agent that prevents oil from passing to the combustion chamber and fuel from getting to the crankcase.
Like every other car component, the Piston rings can wear out over time. Worn-out Piston rings will allow fuel passage to the crankcase, which will result in an oil-gas smell.
#4. Engine Misfire.
Many factors can cause your car’s engine to misfire, including damaged fuel injectors. Regardless of the misfire, there are chances for gas to enter the crankcase during a misfire.
During an engine misfire, all combustion cycles will be affected, hindering adequate air-fuel ignition. During the engine misfire state, the air-fuel mixture will not be completely burnt, which could cause the unburnt fuel to get into the crankcase.
#5. Dirty Fuel.
At one point or the other, some filling stations sell dirty patrol. This dirt can be from the truck that supplied the gas, storage well, or as a result of unrefined petroleum.
When you pour such gas into your vehicle, once this gas gets to the combustion chamber for igniting process, some of the gas will not burn due to the dirt in the gas. Unburnt gas will find its way to the crankcase.
#6. Running Rich Fuel.
All car engines are designed to run with a specific air-fuel ratio. If the fuel injectors or carburetors are sending more fuel than the required amount, the combustion chamber will not burn all the fuel, which will result in fuel passage to the crankcase.
There are many reasons for a rich mixture. Some of the common causes can be damaged MAP sensors, bad mass airflow sensors, or bad oxygen sensors.
#7. No Oil Change.
let’s get this straight! Not changing your engine will not cause the oil to smell like a motorcycle or gas smell directly. It is imperative to note that a small amount of gas entering your engine oil will not impact, and it might not be noticeable.
However, if this small amount of gas passage is built up in your crankcase and you fail to change your oil regularly, you will start noticing the gas smell in the engine oil once the fuel passes 2.5% of the oil quantity.
#8. Pouring gas instead of oil.
Someone might sporadically pour gas in an engine oil port instead of engine oil. One of the common reasons why one might pour gas instead of motor oil is mixing up containers. Some folks use containers to buy both gas and engine oil.
They might mistake these containers for each other. Hence, you should avoid using random containers.
#9. Stuck Fuel injectors.
The fuel injectors are designed to close themselves automatically after sending the right amount of fuel to the combustion chamber. If the fuel injectors become faulty, they might get stuck open and pour excess fuel into the cylinder walls.
When this happens, you’ll notice oil smells like a lawnmower. If the excess gas in the crankcase gets too much, it can cause catastrophic engine damage.
What are the Symptoms of an Oil-gas Mixture?
When your car’s oil emits a distinct smell of gasoline, it’s crucial to recognize the signs and symptoms indicating potential issues within your vehicle. Here are some key indicators to be aware of:
- Strong Gasoline Odor: One of the most obvious signs is a noticeable smell of gasoline coming from your car’s oil dipstick or oil filler cap. This distinct odor is often a clear indication of fuel contamination in the engine oil.
- Discolored Oil: Gasoline contamination can cause the engine oil to appear lighter or thinner than usual. It may take on a milky or caramel-like color, indicating the presence of fuel mixed with the oil.
- Decreased Oil Level: If you notice a sudden drop in your car’s oil level without any visible signs of leaks, it could be a result of gasoline dilution. Fuel mixing with the engine oil can cause the oil level to rise, leading to overfilling, or it may evaporate due to increased volatility.
- Engine Performance Issues: Gasoline-contaminated oil can compromise engine performance. You may experience rough idling, misfires, reduced power, or hesitation during acceleration. These symptoms occur as a result of poor lubrication and combustion inefficiency.
- Increased Fuel Consumption: Fuel contamination can affect fuel efficiency as well. If your car’s oil smells like gas, it may be burning excess fuel, leading to higher fuel consumption and reduced mileage.
- Check Engine Light: In some cases, a gasoline smell in the oil can trigger the check engine light to illuminate on your dashboard. This warning sign indicates that the engine management system has detected a fault related to fuel mixture or combustion issues.
- Excessive Exhaust Smoke: Gasoline-contaminated oil can produce excessive exhaust smoke, often appearing bluish or grayish in color. This smoke results from burning oil mixed with fuel, indicating potential internal engine problems.
What will happen if oil goes into the crankcase?
There are no instant effects for an oil-gas mixture. However, if much gas finds its way to the crankcase or a small amount of gas stays in the crankcase for long, there will be some consequences that you’ll need to be aware of.
- Affecting Oil Viscosity: Oil is more viscous than fuel, making it more suitable for lubrication than gas. If a large amount of gas enters the oil pan or small gas leaks into the oil pan and stays there for long, the oil will lose its viscosity.
- Fast Wear and Tear: Once the motor oil loses its viscosity and lubricating power, your internal engine components will begin to wear out faster. Oil Viscosity prevents internal engine components from wearing out. Therefore, preventing or solving the oil-gas mixture will save you hundreds of dollars in repair costs.
- Overheating Engine: If the oil loses its lubricating power and becomes less viscous, it will not cool down quickly. An Overheating engine can stop running. It will also cause severe engine damage, like a blown head gasket.
- Lost of Gas and Reduction in fuel Economy: If excess fuel finds its way to the crankcase, then you’re losing a tremendous amount of fuel. When this happens, you will have less engine power and a significant drop in your fuel economy.
How to Diagnose a Gasoline Smell in Your Engine Oil?
If you suspect a gasoline smell in your engine oil, follow these steps to diagnose the problem:
- Check the Oil Dipstick: Pull out the dipstick and examine the oil. Not only smell it, but also look for changes in color and consistency. Oil contaminated with gasoline will appear thinner and may have a lighter color than usual.
- Monitor Oil Level: Frequently check your oil level. If you notice a sudden increase in oil level, combined with the gasoline smell, it strongly suggests fuel contamination.
- Check for Other Symptoms: Look out for other symptoms that may accompany gasoline-contaminated oil.
- Decreased Fuel Economy: Noticeably lower miles per gallon.
- Rough Idling or Misfiring: The engine may run unevenly or experience occasional misfires.
- Excessive Exhaust Smoke: Look for thick, black smoke coming from the exhaust, which indicates incomplete combustion.
- Check Engine Light: The check engine light may illuminate, signaling a potential problem with the fuel system or engine.
How To Fix Oil Smelling Like Gas?
Once you smell gas in the oil, it’s time to take action. Hopefully, the problem is nothing serious, allowing you to perform a quick fix and get back on the road. However, if you don’t resolve the situation, it could turn into something larger.
Here are the steps we would take as professional mechanics.
#1. Drive More Often And For Longer.
It’s important to start off by evaluating how you drive. Driving short distances isn’t good for the car and it can lead to a gas smell. To change this, consider combining trips, so you are out for a longer period at once.
You need to drive long enough for the engine to reach a higher operating temperature. That’s when the gas will start to burn out of the oil pan, so you no longer have that smell anymore.
#2. Check Trouble Codes.
If there’s a Check Engine Light on, you want to read the codes to see what’s causing the problem. Plug in your OBDII scanner and see what codes show up. You may also use freeze frame data to determine what’s going on.
If you aren’t familiar with the DTCs, you can reference the information with our online code library. Perform whatever fix seems relevant and reset the codes to see if the problem resolves itself. If not, you should continue working through our steps.
#3. Check Compression.
An engine compression test checks the pistons’ and valves’ ability to compress the air and fuel mixture. You don’t need a lot of mechanical experience to perform the test, but you will need some specialized tools.
Here are some basic steps to follow.
- Gather your equipment: You don’t want to search for your tools after you get started. You can rent one locally if you don’t have a compression tester.
- Disable fuel/ignition: The engine cannot run during the testing. Older vehicles with a distributor can be disabled at the coil. Fuel-injected cars need to be disabled at the fuel system. Look in the owner’s manual to find the fuel pump fuse and remove it.
- Take out the spark plugs: During the testing, you don’t want compression strokes hindering the spinning.
- Start the test: Hook up the compression testing tool. Spin the engine at least six times for the gauge to read properly. Keep your hands clear of all pulleys and belts.
- Record your readings: Write down the readings as you go for reference. Most gas engines have a compression between 125 and 175 PSI.
- Evaluate the reading: If one reading is lower than the others, there might be a problem with a cylinder. If you have several lower numbers, other engine issues may be present.
Remember to hook everything back up after the compression test. If you’ve disabled the fuel or ignition system, it’s time to put it back together.
#4. Change Engine Oil.
If it’s time to change the oil, you may consider seeing if this fixes your problem. Most cars with conventional oil need to be changed every 3,000 miles.
If you use synthetic motor oil, you may be able to go 7,500 miles or more. Check the service schedule for your particular car model to get accurate information.
Here are some basic steps to consider.
- Jack up the car and secure it on jack stands.
- Place an oil drain pan under the oil plug and open it.
- Allow the oil to drain out completely.
- Remove the old oil filter.
- Put the drain plug back in.
- Install the new oil filter.
- Fill the system back up with oil.
- Check the levels and top off as needed.
It’s also important to check for leaks. If you notice any leaks, you want to fix them before the problem gets worse.
#5. Contact A Professional.
If you need to find a mechanic, talk to your family and friends to see who’s recommended. The Federal Trade Commission also recommends asking to see current licenses from the mechanic.
You may have to pay for the diagnostics, but the shop should give you a detailed estimate before performing a bunch of repair work. Sometimes, it’s just better to pay this bill versus banging your head against the wall trying to figure out what’s wrong.
What to Do if Your Engine Oil Smells Like Gas
We’ve got you covered with a step-by-step action plan:
- Confirm the Issue: First, let’s be sure you’re actually dealing with gasoline in the oil. Take out the dipstick, check the oil’s appearance and smell. If it’s distinctly different from the usual, it’s likely fuel contamination. A good trick is to compare the smell with that from the fuel tank cap to confirm your suspicions.
- Check for Simple Causes: Sometimes, it’s as simple as your engine not warming up properly due to short trips. Reflect on your recent driving habits; they might be contributing to the problem.
- Inspect Common Culprits: If you’re not a car engine expert, your best bet is to visit your mechanic. Diagnosing the issue without hands-on experience and the right tools can be challenging. Discuss the potential culprits we’ve talked about earlier with your mechanic.
- Change the Oil: If you need to keep using your vehicle and the smell isn’t just from short trips, I’d recommend changing the engine oil first. If you’re leaving the car at a shop or planning to diagnose and repair it yourself, wait to change the oil and filter until after resolving the issue.
- Monitor the Situation: Post-repair and oil change, keep a close watch on your car’s performance and oil condition. Regular checks will help ensure the problem doesn’t come back and your engine stays in top shape.
Remember, promptly addressing gasoline in your engine oil can prevent more severe and expensive engine issues down the road. It’s all about safeguarding your vehicle’s heart.
Long-Term Effects of Ignoring the Problem
Ignoring the smell of gasoline in your engine oil can have serious consequences:
- Engine Damage: The diluted oil loses its lubricating properties, increasing friction and wear on engine components. This can lead to premature engine failure.
- Catalytic Converter Damage: Unburned fuel entering the exhaust system can damage the catalytic converter, a costly component to replace.
- Reduced Fuel Economy: Gasoline contamination affects engine performance and reduces fuel efficiency.
Financial implication
Ignoring the smell of gasoline in your car’s oil can have significant financial implications, both in the short and long term. Here’s how neglecting this issue can impact your finances:
Increased Maintenance Costs
Gasoline contamination compromises the effectiveness of engine oil, leading to accelerated wear and tear on critical engine components.
Over time, this can result in the need for more frequent oil changes, engine flushes, and repairs to address damage caused by poor lubrication. These additional maintenance expenses can quickly add up, draining your wallet unnecessarily.
Expensive Repairs
Failure to address gasoline contamination promptly can lead to more severe engine damage, necessitating costly repairs or even engine replacement.
Repairing or replacing damaged components such as piston rings, bearings, or cylinder walls can be significantly more expensive than addressing the initial issue early on.
Delaying repairs may also result in collateral damage to other engine parts, further increasing repair costs.
Decreased Resale Value
A car with a history of neglected maintenance and engine problems, such as gasoline contamination, is likely to have a lower resale value.
Potential buyers may be wary of purchasing a vehicle with known mechanical issues, leading to decreased demand and a lower selling price.
Addressing the problem promptly can help preserve your car’s resale value and attract potential buyers willing to pay a higher price.
Voided Warranties
Ignoring engine-related issues, including gasoline contamination, may void manufacturer warranties or extended warranty coverage.
Most warranties require regular maintenance and prompt repairs to remain valid. Failing to adhere to these requirements could leave you responsible for covering repair costs that would otherwise be covered under warranty, resulting in unexpected expenses.
Emergency Expenses
Ignoring warning signs of gasoline contamination increases the risk of sudden breakdowns and roadside emergencies.
In addition to the inconvenience of being stranded, emergency repairs conducted outside of regular maintenance schedules often come with premium costs for towing, roadside assistance, and expedited repairs.
These unexpected expenses can strain your budget and disrupt your financial plans.
Prevention
To keep your engine running as it should and avoid the issue of motor oil smelling like gas, there are several things you can do as part of regular maintenance.
- Regularly check oil level and viscosity for proper lubrication
- Monitor piston rings and fuel injectors for potential issues
- Ensure oxygen sensor and spark plugs are functioning properly to maintain air-to-fuel ratio
- Avoid driving short distances too often to prevent engine wear and oil dilution
- Inspect and service crankshaft as needed to prevent excess fuel entering motor oil
- Change your oil according to recommended mileage or time intervals. Yes, old oil can go bad.
FAQs.
Q: Is it bad if your oil smell like gas?
If your engine has a gas smell, it is most likely you have an oil-gas mixture. If the gas stays for long in the crankcase, it will affect your oil lubricating power and make it less viscous. When this happens, your engine’s internal components will wear out faster.
Q: Will gas evaporate out of gas?
If you notice oil smells like Reddit, which indicates a gas-oil mixture, you might want to ask if the gas will evaporate out of oil.
Yes, gas will evaporate out of oil when you have a long-distance drive that will heat the crankcase enough that it will allow the gas to escape as vapor.
Q: Is 2-year-old gas still good?
Gas degradation usually starts from the get-go, a gas that is a month or two old is still okay, but when it gets to 1year old, it is recommended that you change it.
However, allowing your gas to stay up to 2 years old, can cause engine problems like fuel injection problems. We recommend always use good quality gas can for carrying the gas for disposal.
Q: Is it okay to mix old gas with new gas?
Old gas will lose its potency once it gets up to a year, leading to rough running and engine misfiring. So can you mix old gas with new gas?
Yes, but you should ensure that the amount of old gas you intend to mix with new gas should not be more than 25% of the total amount of gas in your gas tank.
Final Thought
At this point, you must have known how to fix issues associated with gas getting into an oil lawnmower. With this article’s help, you can quickly tell the causes of oil smelling like gas and what will happen if gas goes into the crankcase.
You might notice just one or two of the outlined symptoms when gas goes into the crankcase. Once you see any of these symptoms, you want to do the necessary things like driving a long distance and doing a regular oil change.