Do you smell gasoline in your engine oil? This is an alarming odor indicating an issue with serious oil dilution that allows fuel to get where it doesn’t belong, and left untreated it will eventually ruin your engine.
But don’t panic, since you can get some idea of what’s going on and take action before it becomes disastrous.
Possible Reasons Your Oil Smells Like Gas
Oil in an engine can become contaminated with gas for several reasons, some more serious than others. Here are several possible reasons for the onset of this issue.
#1. Injector Issues.
When the injector is working properly, it atomizes the fuel each time it pop off and allows it to burn really well and at the highest efficiency.
As injectors get older, they tend not to atomize the fuel in the same way and get a proper burn. Thus, unburnt fuel can wash past a piston ring in the cylinder and eventually get into the engine oil.
#2. Ignition System Failure:
The ignition system in an engine has multiple components that work together to ignite the fuel that is delivered into the cylinder of an engine.
If any of these components fail (such as a bad spark plug), fuel can be left unburnt in one or more cylinders. If it is bad enough, the fuel can wash by the piston rings, at which point it mixes with oil in the sump.
#3. Excessively Rich Air/Fuel Ratio.
In some cases, one or more faulty sensors have tricked the engine’s electronic control module into injecting too much fuel for the condition, causing a “rich” condition in which the engine can’t burn the fuel injected.
This also means that excess fuel washes past a cylinder’s rings and mixes with the oil below.
#4. Internal Engine Wear.
In rare cases, a mixture of oil and gas can result from internal engine wear. When cylinder walls or piston rings become excessively worn, proper combustion will have a greater chance of being hindered.
As a result, a significant amount of fuel often goes unburnt and washes down the cylinder walls, increasing the chances of wear on an engine’s bearings.
#5. Infrequent Oil Changes.
In any case, an extremely small amount of fuel usually ends up in the oil, regardless of any mechanical problems. In the event of fuel contamination, the risk is usually minimal and not a threat to an engine’s reliability or longevity.
However, if the oil is not changed on a timely basis, the amount of fuel may build up, typically but not always detected by the odor of gasoline.
#6. Continuous Short Distance Trips.
Newer vehicles with OBD-II systems are programmed to run rich during cold starts and transition to a leaner air/fuel ratio once the engine reaches operating temperature.
This ensures that the vehicle has enough fuel to prevent stalling and poor performance when cold.
However, if the vehicle is constantly driven for short excursions, this rich condition can lead to an oil dilution problem sooner or later.
Diagnosing the Issue
First of all, look for any white smoke coming from the exhaust. White smoke could be a sign that the fuel is mixing with the engine oil, which would indicate a problem.
You should also consider the check engine light. If any engine components are malfunctioning, it could illuminate.
Also, remember that engine misfiring can also be a sign of a problem. If your engine misfires, there is a chance that gasoline is entering the crankcase, and that might be the explanation for the oil-gas smell.
There are a number of different issues that could potentially cause engine misfiring, such as a broken fuel injector or bad piston rings, or a bad oxygen sensor.
Finally, you will want to monitor the performance of your engine. If it feels sluggish or is losing power, this could be the result of an oxygen sensor or too rich a fuel mixture.
Prevention
To keep your engine running properly and to prevent the problem of motor oil smelling like gas, there are several steps you can take during routine maintenance.
- Examine oil level and viscosity regularly for proper lubrication.
- Monitor piston rings and fuel injectors for possible complications.
- Check that the oxygen sensor and sparkplugs are in working condition to keep the air-to-fuel ratio.
- Limit short-distance trips to help minimize engine wear and oil dilution
- Examine and service the crankshaft as needed to prevent too much fuel from getting into the motor oil.
- Follow the manufacturer’s recommended mileage or time interval for oil changes. Yes, old oil does go bad.
FAQs.
Q: Is Gasoline in Oil Visible?
Gasoline is often not visible when mixed with engine oil. In fact, this contamination is much more likely to result in a noticeable thinning of oil. This “thinning” results in oil appearing much more translucent than normal.
Gasoline-contaminated oil will also tend to feel especially thin to the touch. If you rub a small amount of contaminated oil between your thumb and index fingers, you will observe this thinning, and the oil will have a relative loss in viscosity, which can lead to increased bearing wear.
Q: Is It Safe to Drive If You Smell Gas in Your Engine Oil?
It’s not, in general, a good practice to drive a vehicle containing a detectable amount of gasoline in the engine oil.
This practice puts the integrity of the engine at great risk since gas thins the oil, lowering viscosity and accelerating wear to essential parts of an engine, like the bearings.
Not to say that driving a vehicle with fuel-diluted oil will result in catastrophic engine failure instantly for the engine.
However, driving a vehicle with diluted oil brings an extremely high risk and is likely to cause damage, even if it does not appear immediately.
It is best to avoid driving a car that, upon inspection, shows any gasoline smell in the engine oil.
However, if you must drive the affected vehicle, certain precautions should be taken. First, the oil and oil filter should be changed.
When changing the oil, an oil sample can be taken for further analysis, so it can be sent off for testing and confirmation regarding any suspensions of oil rinsed oil you might have.
Ultimately, the reason for an engine’s oil dilution should be diagnosed and repaired as soon as possible.
Taking these precautions will maximize the chances of avoiding secondary issues, whichever they may be, from driving a vehicle with anything less than pure oil diluted with gas, if there are any secondary issues.
If you are not comfortable repairing, it is best to make an appointment with your service center as soon as possible.
Q: Is It Normal to Smell Gas After an Oil Change?
After an oil change, you may smell gas in some cases due to residual gasoline mixing with the new oil. If the odor continues or gets stronger, then it could be an actual issue. Watch for a while, and if it continues, take it to a mechanic.
Q: Does Fuel in Oil Burn Off?
Yes, the fuel, when it is a small amount in your engine oil, will burn off as the oil reaches operating temperature, but it will depend on the amount of gas you’re talking about and where you drive.
Q: Is It Uncommon for Engine Oil to Smell Like Gas in Some Vehicles?
Under a normal process, engine oil should not smell like gas, but it can smell like gas if you’re regularly driving short distances, don’t get your oil changed, or if there is a mechanical issue.
Q: Can Gas in Engine Oil Cause White Smoke?
Yes, gas in your engine oil can cause an exhaust with white smoke because gasoline mixed with oil causes a problem like burning less fuel and oil.
White smoke is a telltale sign that your engine is burning oil in the fuel. This can hinder your vehicle’s performance and may damage it in the process.