Can Burning Oil Damage Catalytic Converter? The Details

Catalytic converters are essential components of modern vehicles, playing a crucial role in reducing harmful emissions and keeping the environment cleaner. They help convert the toxic gases and pollutants in your car’s exhaust gas to less harmful pollutants by catalyzing a redox reaction. However, several factors can contribute to the damage of a catalytic converter, one of which is burning oil. This article will explore can burning oil damage catalytic converter, the cleaning of clogged cat, and ways to prevent it.

will burning oil clog a catalytic converter

The Role of the Catalytic Converter

The catalytic converter is a component of the exhaust system that contains a honeycomb structure coated with catalysts such as platinum, palladium, and rhodium. These catalysts facilitate the conversion of harmful gases like carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC) into less harmful substances like carbon dioxide (CO2), nitrogen (N2), and water vapor (H2O).

Can Burning Oil Damage Catalytic Converter?

Burning oil in an engine can negatively affect your catalytic converter. The engine oil doesn’t directly clog the catalytic converter; the byproducts of burning oil create conditions that can lead to the converter’s clogging, reduced effectiveness, and even complete failure. Here’s how:

Formation of Carbon Deposits:

When engine oil finds its way into the combustion chamber—often due to worn piston rings, valve guides, or defective valve stem seals—it burns and creates carbon deposits and ash. These substances can result oil leaking in the exhaust system and accumulate on the catalytic converter’s honeycomb structure, effectively clogging it and reducing its ability to convert harmful gases.

Contaminant Coating:

Burning oil produces various byproducts, such as phosphorus and sulfur. These elements can adhere to the catalyst materials inside the converter, inhibiting their effectiveness in facilitating necessary chemical reactions. Essentially, the catalytic material gets ‘poisoned,’ making it less efficient at reducing harmful emissions.

Air-Fuel Ratio Imbalance:

The presence of oil in the combustion chamber can skew the optimal air-fuel mixture, leading to incomplete combustion. Incomplete combustion produces more pollutants and makes it harder for the catalytic converter to process and neutralize these pollutants, causing it to work harder and less efficiently.


A compromised catalytic converter may have to work harder to achieve its emission-reducing functions, causing it to overheat. Excessive heat can melt the internal honeycomb structure, rendering the converter ineffective and requiring replacement.

Thus, it is essential to address oil burning issues promptly to protect your catalytic converter and

How to Prevent Oil in Catalytic Converter?

Use Better Quality Oil

Preventing oil from entering the catalytic converter is essential for maintaining the component’s longevity and efficiency. Oil in the catalytic converter usually originates from the engine, which is burned due to various mechanical issues. Here are some preventive measures:

  1. Regular Oil Changes: One of the most straightforward ways to keep your engine healthy is through regular oil changes. Old, dirty oil is more likely to create sludge and deposits that can lead to problems.
  2. Fix Leaks: Any engine or oil system leaks should be promptly addressed. Oil leaks can contribute to oil burning and eventually lead to issues with the catalytic converter.
  3. Replace Worn Components: Piston rings, valve seals, and valve guides can wear out over time, allowing oil to seep into the combustion chamber. Replacing these components at the first sign of wear can help prevent this.
  4. Engine Tune-Ups: Regularly scheduled engine maintenance, including air filter changes and spark plug replacements, can improve combustion efficiency, reducing the likelihood of oil burning.
  5. Use High-Quality Oil: Always use the type of oil recommended by your vehicle’s manufacturer. High-quality oils are less likely to form deposits that can lead to oil leakage into the combustion chamber.
  6. Check PCV Valve: The Positive Crankcase Ventilation (PCV) valve helps control the emission of fumes from the crankcase. A malfunctioning PCV system can lead to oil being drawn into the combustion process.
  7. Monitor Oil Levels: Regularly check your oil levels and look for signs of excessive consumption, which can indicate a problem that could eventually affect your catalytic converter.
  8. Oxygen Sensors: Keep an eye on your oxygen sensors, as malfunctioning sensors can cause a rich fuel mixture that may lead to excessive carbon deposits, indirectly leading to oil entering the combustion chamber.
  9. Early Diagnosis and Repair: If you experience symptoms of catalytic converter issues or oil burning, such as reduced engine performance, smoke in the exhaust, or the “Check Engine” light coming on, get your vehicle checked by a professional immediately.

By taking these preventative measures, you can substantially reduce the risk of oil entering your catalytic converter, extending its lifespan and maintaining the overall health of your vehicle.

How to Clean an Oil-clogged Catalytic Converter?

The topic of cleaning catalytic converters is subject to some debate within the automotive community. While many experts recommend replacing a failed or clogged catalytic converter, some methods aim to clean and restore these devices. However, success varies, and it’s crucial to note that cleaning may not always resolve the underlying issues that led to the problem in the first place. Here’s a look at some common approaches to cleaning a catalytic converter:

DIY Cleaning Methods

  1. Fuel Additives: There are products on the market designed to clean the catalytic converter as part of a fuel additive package. These additives claim to remove carbon deposits from the engine and exhaust system, including the catalytic converter, during combustion. However, their effectiveness is limited and unlikely to resolve severe clogging or other mechanical issues.
  2. High-Speed Drive: Taking your car on a high-speed drive on the highway for an extended period can heat the catalytic converter to temperatures that may burn off some deposits. This “Italian tune-up,” sometimes humorously called, is rarely a guaranteed or long-term fix.
  3. Removal and Soaking: Some people remove the catalytic converter and soak it in a mixture of degreaser and water. After soaking, the unit is dried and reinstalled. However, this method is labor-intensive, can void your warranty, and poses a risk of damaging the sensitive catalyst coating.
Cleaning Catalytic Converter YouTube

Professional Cleaning Methods

  1. Ultrasonic Cleaning: Some specialized services offer ultrasonic catalytic converter cleaning. This method involves removing and submerging the converter in a water and detergent solution while subjected to ultrasonic waves. This can help remove accumulated deposits effectively but is often expensive.
  2. Oxygen Sensor Replacement: Sometimes, replacing a faulty oxygen sensor can resolve issues that appear to be related to a “clogged” or inefficient catalytic converter. The oxygen sensor plays a critical role in monitoring and optimizing the air-fuel mixture for combustion, affecting the operation of the catalytic converter.

Precautions and Recommendations

  1. Diagnosis: Before attempting to clean a catalytic converter, it’s essential to properly diagnose the issue to ensure that the cleaning will solve the problem. Sometimes, the issue may lie elsewhere in the engine or exhaust system.
  2. Check Warranty: Before attempting DIY methods, check if your vehicle’s warranty covers catalytic converter replacement. Tampering with the unit could void the warranty.
  3. Consult Professionals: For severe issues, consult with a professional mechanic. Sometimes, replacement is the only effective solution, especially if the internal honeycomb structure has melted or broken apart.

In summary, while some methods claim to clean catalytic converters, their effectiveness varies, and professional evaluation is usually recommended. Replacement is often the most reliable option for a long-term solution, particularly for catalytic converters that have reached the end of their operational lifespan.


Burning oil can damage the catalytic converter by causing clogs, overheating, and eventually leading to its failure. Regular vehicle maintenance, using high-quality oil, and promptly addressing any oil leaks can help prevent such damage. A well-maintained vehicle not only helps safeguard the environment by minimizing harmful emissions but also ensures optimal vehicle performance and longevity.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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