Burning oil smell is a thick, acrid aroma your nose can catch in no time. Most car mechanics call it a “hot smell” since it smells kind of “hot” and a bit plasticy; I’m no exception in this case.
But what does burning oil smell mean? A burning oil smell from a car indicates an oil leak (mostly) or low oil levels. An oil leak can happen from the following sources: drain plugs, valve cover, seals, oil filter housing, and/or oil pan gasket.
When oil drips onto the exhaust system due to these leaks or simply burns other ways, it makes a serious burning smell. Attention please! It is a serious issue with your car. Must read this detailed guide to know its solution.
Car Smells Like Burning Oil After Driving
In around 85% of cases of burning oil I have tackled, the culprit behind it was the oil leak. The remaining 15% of the credit splits between dirty, too-low, or overfilled engine oil.
An oil leak occurs when there is a hole (s) or crack(s) in an oil-carrying component of the engine, such as the oil filter, valve cover gasket, or oil pan. Due to this, the oil drips onto the car’s hot surfaces, engine, or around the engine parts.
The possible reasons for oil leaking in a car include:
- Oil leaking through the valve cover
- Oil leaking into the exhaust system
- PCV Valve leak
- Exhaust leak
- Oil spilled during an oil change
During all these phenomena, the engine oil gets out of the compartment where it stays all the time. It gets in touch with the surrounding surfaces (mostly 250 degrees Fahrenheit hot) and burns there, giving your nose something to sniff off in no time.
When this oil leakage keeps happening for a long time, maybe since your car is losing oil, but you see no leak or smoke, it accumulates excessively in the hot regions of the engine and can pose a significant risk of fire.
A Worn/Bad Valve Cover Gasket
The valve cover gasket, typically made of rubber or a composite material, is responsible for sealing the valve cover located on top of the engine.
If you don’t know, I would like to tell you that this cover houses the camshafts and valves, which are crucial for operating the intake and exhaust valves.
The valve cover gasket ensures proper functioning by preventing oil from escaping the valve cover and reaching other engine components.
If there is a faulty valve cover gasket, oil spills out from the gasket to the car’s engine where it is hot. It can also reach hot zones, such as the exhaust manifold, where it burns.
Symptoms Of A Worn/Bad Valve Cover Gasket
When there is a worn-out bad valve cover gasket, the following happens.
- You can see oil leaks on the engine itself, the ground beneath the vehicle, or even the exhaust manifold.
- A distinct burning oil odor happens when oil seeps onto heated engine parts and vaporizes.
- The engine misfires when the valve cover gasket leaks oil onto the spark plugs.
- The engine’s oil level drops due to oil leakage.
How To Check And Confirm Valve Cover Gasket Is Worn?
The only way to check and confirm whether the valve cover gasket is worn or not is to examine it carefully. Visually inspect the valve cover gasket if you observe oil leaks.
It should be pliable without any cracks or tears. A hard, brittle gasket showing any signs of damage or oil leaks from the sides will require replacement.
Reasons For A Bad Valve Cover Gasket
Two things cause a valve cover gasket to turn bad: age and heat and regular wear and tear due to the repetitive compression and expansion of the gasket.
Solution For A Worn/Bad Valve Cover Gasket
The only way to fix a worn/bad valve cover gasket is to replace it. However, it needs a set of skills and tools. If you are confident in your skills and you can change it yourself, go for it. Otherwise, consult a qualified mechanic to replace the valve cover gasket.
Possible Hazards of a Worn/Bad Valve Cover Gasket
- Engine damage due to oil leaks, insufficient lubrication, increased friction, and heat.
- Damage to surrounding components, such as wiring and electronic parts.
- Oil drips onto hot engine surfaces and potentially ignites, increasing the fire risk.
- Environmental impact due to oil leaks and contamination of soil and water sources.
A Leaked/Bad PCV Valve
The PCV valve (Positive Crankcase Ventilation Valve) is a small valve to regulate the pressure inside the engine by allowing oil vapors to escape from the crankcase and into the intake system. The oil vapors are then burned in the combustion chamber.
Causes Of Leaked PCV Valve
Cracks and/or blockages in the vacuum hose connected to the PCV valve are the primary underlying causes of a malfunctioning PCV valve.
Symptoms Of A Leaked PCV Valve
A leaked PCV valve experiences a leak, leading to increased pressure within the valve cover as it can’t be able to regulate the ventilation of the engine properly.
The engine will consume more oil due to a faulty PCV valve since the oil vapors can escape from the crankcase and into the intake system, where they are not burned.
Is PCV Valve Really Leaked? This Is How To Confirm It.
Find the PCV valve in your vehicle. It is usually connected to a hose and may be secured with a clamp or housed in an L-shaped housing at the end of the hose.
If there is a clamp holding the hose in place, loosen it. If an L-shaped housing covers the valve, attentively detach it from the valve.
Depending on the type of PCV valve, it may be held in place with a rubber grommet or threaded into place. If it is held by a grommet, gently pull the valve free. Use a small crescent wrench or an open-end combination wrench to unscrew it if threaded.
Hold the PCV valve in your hand and shake it gently. Listen for any metallic rattling noise produced during the shaking process.
Pay close attention and listen for any sound when shaking the PCV valve. If you hear a distinct metallic rattling noise, the valve is functioning correctly and likely not leaking.
Note: If you do not hear any sound when shaking the PCV valve, it suggests that the valve is not opening and closing as it should. This lack of sound indicates a potential leakage issue.
Solution For A Leaked PCV Valve
The only way to fix a Leaked PCV Valve is to replace it. The replacement process is simple. If you have confirmed that the leaked/ bad PCV valve is the issue, here is what you can do to replace it.
Remove the older PCV value following the steps I told you in the previous section where I taught you to test the faulty PCV valve.
Once you have taken out the older PCB, install the new valve. If the new PCV valve is threaded, screw it into place by hand to prevent damage to the threads. Ensure that the valve is securely seated, but avoid overtightening.
Reconnect the hose by attaching the hose back onto the PCV valve securely.
Dirty Engine Oil
Dirty engine oil is another reason for a car to smell like burning oil after driving.
When engine oil becomes contaminated with dirt, debris, or other impurities, it can lose its lubricating properties and become less effective at maintaining the engine’s optimal performance.
As a result, the engine may experience increased friction and heat, leading to the oil burning and emitting a strong, distinct odor.
Additionally, the presence of impurities in the oil can contribute to the formation of sludge or deposits, which can further contribute to the burning smell.
Symptoms Of Dirty Engine Oil
The symptoms of dirty engine oil include the following.
Engine Warning Lights — The “oil light” on the car’s dashboard may illuminate, indicating a problem with the engine oil. This could be due to dirty or low oil.
Engine Noise and Knocking — Dirty engine oil can lead to increased friction between engine components, causing unusual engine noises, such as knocking or rumbling sounds.
Dark, Dirty Oil — Clean engine oil is typically golden-brown or amber, but when it becomes dirty, it darkens, sometimes turning completely black.
Burning Oil Smell — A burning engine oil smell, especially when starting the car’s engine, can be a sign of dirty engine oil. Overheating due to oil breakdown can cause this odor.
Exhaust Smoke — If dirty engine oil is not addressed, it can lead to smoke coming from the car’s tailpipe, indicating severe engine issues.
How To Check Engine Oil Is Dirty?
To check if engine oil is dirty, you can follow these steps:
- Park your vehicle on a level surface.
- Turn off the vehicle’s engine and allow it to cool down for a few minutes.
- Find the oil dipstick.
- Remove the oil dipstick from the engine.
- Clean the oil dipstick with a rag.
- Insert the oil dipstick back into the engine.
- Remove the oil dipstick again.
- Check the color of the oil.
Clean engine oil is generally amber or light brown in color. If it’s black or dark brown, it’s dirty and needs to be changed.
How To Change Engine Oil?
To change engine oil, you can follow these general steps:
- Remove the oil cap and loosen the drain plug on the oil pan to let the old oil drain out. After draining, replace the drain plug and remove the old oil filter.
- Pour an engine cleaning solution into the oil reservoir where you pour new oil.
- Allow the cleaning solution to sit in the engine for the recommended time to break down and dissolve sludge and contaminants.
- Drain the solution from the oil reservoir, which will contain dirt and grime.
- Replace the old oil filter with a new one, as the old one may have captured dirt particles.
- Pour new, clean oil into the engine, following the recommended type and amount in your owner’s manual.
- Turn on the vehicle’s engine and let it run for 4-6 minutes to ensure proper circulation of the new oil with no leaks.
Too Low Engine Oil Level
When the oil level in the engine is too low, it can’t properly lubricate the engine’s moving parts. This can cause overheating and wear, which can also cause the oil to break down and burn. Ultimately, your nose will detect that burning smell.
Checking And Confirming The Problem
To check if the oil level is too low, you can use the dipstick, which is located inside a tube on one side of the car’s engine, somewhere around the oil pan. Once located, pull out the dipstick from the tube carefully.
The dipstick will have two marks on it, one for the maximum and one for the minimum. The oil level should be between these two marks. If the oil level is below the minimum mark, it is too low and needs to be topped up.
Interesting Fact: Typically, a four-cylinder car engine requires approximately 4-5 liters of oil, a six-cylinder car engine needs around 5.5 liters of oil, and an eight-cylinder engine typically requires a range of 4.5-7.5 liters of oil.
What Is The Solution To Too Low Engine Oil?
The fix to the issue of too low oil levels is to add more oil to the engine. The amount of oil that requires to be added will depend on how low the oil level is. Make sure to fill just enough engine oil so the mark on the district can reach the midpoint.
Tip: Once the oil level has been topped up, the car should be driven for a short period of time to allow the oil to circulate throughout the engine.
After driving, the oil level should be rechecked to ensure it is still between the maximum and minimum marks.
If the oil level continues to drop, it may indicate a more severe engine issue. In this case, having the car checked by a mechanic is important.
Overfilled Engine Oil
It may seem a bit impossible, but if the oil level in the engine is too high, it can be a reason behind the burning smell of your car.
Too-high oil levels in the engine can force oil past the piston rings and into the combustion chamber, where it will be burned and create a burning smell.
If the oil level in the engine is too high, it can force oil past the piston rings and into the combustion chamber, where it will be burned and create a burning smell.
This Is How To Check Overfilled Engine Oil
To check if the engine oil is overfilled, you can use the dipstick that is located near the engine. The dipstick will have two marks on it, one for the maximum and one for the minimum.
The oil level should not be above the maximum mark. If the oil level is above the maximum mark, it is overfilled and requires to be drained.
What Is The Solution To Overfilled Engine Oil?
The solution to the overfilled engine oil problem is simple: drain some of the oil from the engine, depending on how much oil is above the maximum mark on the dipstick. As I mentioned earlier, the oil level should be between the maximum and minimum mark.
How To Drain Excessive Engine Oil?
Turn Off the Engine and Open the Vehicle’s Hood. Begin by turning off your vehicle’s engine. Then open the hood and ensure you have an oil pan ready.
Remove the Drain Plug and Drain the Oil. Position the oil pan underneath the vehicle to catch the oil. Spot the drain plug on the oil pan or engine block and use a suitable tool to unscrew it.
Let the oil drain thoroughly into the pan. Remember that the draining process may take some time, depending on the temperature and viscosity of the oil.
Replace the Drain Plug. Once all the oil has been drained, securely screw the drain plug back into place.
Ensure it is tightened properly to avoid any leaks. Remove any oil residue from the engine cap and place a funnel into the oil filler opening.
Pour the Appropriate Amount of Oil. Slowly pour the right amount of oil into the funnel. Be cautious not to pour all the oil at once.
I suggest you pour the oil in increments and periodically check the oil level using a dipstick. Add oil gradually until the engine has reached the recommended level.
Replace the Engine Cap and Close the Hood. Once the engine has the appropriate oil level, replace the engine cap and securely close the hood of the vehicle. The excess oil collected in the oil pan can be stored for future use when needed.
Can A Transmission Leak Smell Like Burning Oil?
Yes, a transmission leak can produce a smell similar to burning oil. Despite being an expert, I can often mistakenly consider it an oil leak due to the same smell.
When transmission fluid leaks, it can come into contact with hot engine components or the exhaust system, leading to the fluid being heated and producing a burning smell.
The presence of a burning smell from the transmission area is a significant indication that something may be wrong with the transmission.
If you have ruled out any engine or oil-related problems and still notice the burning smell, I suggest immediately inspecting the condition and level of the transmission fluid.
Check for any signs of leakage and take care of the issue promptly to avoid further damage to the transmission and ensure the proper functioning of your vehicle.
Should I Drive My Car If It Smells Like Burning Oil?
I DO NOT recommend keeping your car driving if it smells like burning oil. This is because a burning smell typically happens due to oil leaks. And if you don’t check and resolve the issue, there is the risk of fire in the compartment.
Immediately pull over safely and examine the engine. Go straight to your mechanic if you see an oil leak. Even if you don’t see a leak but the “hot smell” of the oil stays there after driving for 20 minutes, I advise consulting an expert mechanic.
How Much Does It Cost To Repair “Hot Smell” Issue?
The cost to repair the burning engine oil smell depends on what is causing it. Most of the time, an oil leak repair can cost about $100 to $2,000, depending on the source.
If a worn oil drain plug gasket is responsible for the leak, the repair cost will likely be approximately $35. However, if the issue lies with the oil pan, be prepared for a range between $100 and $500.
Is It OK To Smell Burning Oil?
For short-term exposure, there won’t be much effect of the burning oil smell on someone’s health, but long-term exposure to such a smell can cause serious health problems. This is because burning oil smoke contains unhealthy gasses and toxins.
George Alexander is a seasoned automotive expert, boasting an impressive background in the industry. Having spent considerable time in a range of mechanical garages, he has developed a profound understanding of diagnosing and repairing various types of vehicles, including cars, SUVs, and ATVs.
His unwavering dedication to resolving vehicle faults has earned him a reputation as the go-to person for all your car-related concerns. With his extensive knowledge and hands-on experience, he excels at troubleshooting issues and finding effective solutions that ensure optimal performance and longevity for your vehicle.