What Causes Metal Shavings in Oil?

person pouring new oil into car engine

Metal shavings, also known as metal particles or swarf, are small, thin, and often irregularly shaped pieces of metal that can be produced as a result of friction between moving parts in an engine or during a machining process. In the context of automotive engines, these shavings may find their way into the engine oil, potentially causing damage if left unaddressed.

Clean oil plays a crucial role in maintaining the health and longevity of an automotive engine. It serves as a lubricant, reducing friction between moving parts and minimizing wear and tear. Additionally, engine oil helps to dissipate heat, keeping the engine at an optimal operating temperature, and it also acts as a cleaning agent, removing dirt and contaminants from the engine. The presence of metal shavings in the oil can compromise its effectiveness, potentially leading to accelerated wear, overheating, and even catastrophic engine failure.

Metal shavings can find their way into the engine oil for various reasons, including normal wear and tear, manufacturing defects, poor lubrication, or damage to engine components. It’s essential to understand the different causes and the appropriate actions to take in order to maintain a well-functioning and long-lasting engine. In this article, we will discuss the primary causes of metal shavings in engine oil, preventive measures and maintenance practices, and what to do if you encounter this issue in your vehicle.

Normal Wear and Tear

Even in the best-maintained vehicles, some degree of wear and tear is inevitable due to the constant friction between moving engine components. Over time, this can result in small metal shavings finding their way into the engine oil. It’s essential to understand which parts are prone to wear and how to recognize the signs of normal wear and tear to ensure your engine continues to function optimally.

Engine Components Breakdown


Bearings are crucial in reducing friction between various rotating components within an engine, such as the crankshaft and connecting rods. As the engine operates, these bearings gradually wear down, producing tiny metal shavings. This is a normal process, and as long as the shavings are minimal and irregularly shaped, there is no cause for concern. Regular oil changes and using the appropriate oil can help prolong the lifespan of your engine bearings.

 Piston rings

Piston rings are circular metal bands that fit around the pistons in an engine. They serve multiple purposes, including sealing the combustion chamber, regulating oil consumption, and transferring heat from the piston to the cylinder wall. Over time, the constant motion of the pistons and the high pressures within the combustion chamber can cause the piston rings to wear down, generating small metal shavings. Regular maintenance, including timely oil changes and ensuring the engine remains cool, can help minimize wear on piston rings.


The cylinders in an engine are where the combustion process takes place, and they house the pistons and piston rings. As the pistons move up and down within the cylinders, a small amount of wear can occur on the cylinder walls. This wear can result in tiny metal shavings entering the engine oil. Keeping your engine well-maintained, with clean oil and a properly functioning cooling system, reduces wear on the cylinders and can extend the overall life of your engine.

Indicators of Normal Wear and Tear

Recognizing the signs of normal wear and tear is essential for distinguishing between typical engine operation and potential issues that may require immediate attention. Here are some indicators that the metal shavings in your engine oil are likely due to normal wear and tear:

Small, irregularly shaped shavings

When wear and tear is typical, the metal shavings you may find in your engine oil tend to be small and irregularly shaped. These tiny particles usually do not pose a significant risk to your engine’s performance or longevity, as they will be captured by the oil filter and removed during regular oil changes. However, if you notice an increase in the number or size of these shavings, it may be a sign of a more severe issue that requires further investigation.

Gradual accumulation

Under normal operating conditions, the accumulation of metal shavings in your engine oil will be gradual. This means that you should not see a sudden increase in the amount of metal debris when performing routine maintenance checks. Regular oil changes and following the manufacturer’s recommendations for your vehicle will help ensure that any metal shavings resulting from normal wear and tear are removed from the engine, preventing them from causing further damage or issues.

Abnormal Wear and Excessive Metal Shavings

While some metal shavings in engine oil can be attributed to normal wear and tear, excessive amounts or certain types of shavings may indicate a more serious issue. Understanding the causes and signs of abnormal wear is essential for taking appropriate action to prevent further damage to your engine.

Causes of Abnormal Wear

 Poor lubrication

Inadequate lubrication can result from using the wrong type of oil, infrequent oil changes, or low oil levels. Poor lubrication can lead to increased friction between engine components, causing excessive wear and producing a higher volume of metal shavings. Regularly checking and changing your engine oil according to the manufacturer’s recommendations can help prevent this issue.


An overheating engine can cause metal components to expand, leading to increased friction and wear. This can result in a greater number of metal shavings in the engine oil. Ensuring that your engine’s cooling system is functioning correctly and addressing any overheating issues promptly can help prevent abnormal wear.

Misaligned or damaged parts

Engine components that are misaligned, damaged, or improperly installed can create uneven wear patterns and lead to excessive metal shavings in the oil. Regular inspections and addressing any issues with your engine’s components can help minimize abnormal wear.

Manufacturing defects

In some cases, manufacturing defects in engine components can cause abnormal wear and lead to excessive metal shavings in the oil. If you suspect that a defect is the cause of the issue, consult with a professional mechanic or contact the manufacturer for further guidance.

Indicators of Abnormal Wear

Large, sharp, or uniform shavings

The presence of large, sharp, or uniformly shaped metal shavings in your engine oil may be a sign of abnormal wear. These shavings can indicate a more significant issue requiring immediate attention to prevent further damage to your engine.

Rapid accumulation

A sudden increase in the number or volume of metal shavings in your engine oil could indicate abnormal wear. Rapid accumulation of metal shavings may mean a severe issue that requires prompt investigation and repair.

Changes in engine performance or noise

Abnormal wear can lead to changes in engine performance, such as reduced power, decreased fuel efficiency, or increased noise. If you notice any of these symptoms along with excessive metal shavings in your oil, it is essential to consult with a professional mechanic to identify and address the underlying issue.

Warning signs on the dashboard

Some modern vehicles are equipped with sensors that can detect excessive metal shavings in the oil and trigger a warning light on the dashboard. If you see a warning light related to your engine’s oil or performance, it’s crucial to have your vehicle inspected as soon as possible to determine the cause and address any potential issues.

Preventive Measures and Maintenance

Regular Oil Changes

  • Use the right oil: Ensure you use the correct type and grade of oil for your vehicle, as specified by the manufacturer.
  • Follow recommendations: Adhere to the manufacturer’s guidelines for oil change intervals to maintain optimal engine performance.

Proper Engine Cooling

  • Maintain the cooling system: Regularly check coolant levels and inspect hoses and belts for wear or damage.
  • Avoid overheating: Monitor your engine temperature and address any overheating issues promptly.

Periodic Inspections and Repairs

  • Check for misaligned or damaged parts: Inspect your engine for any signs of damage and ensure all components are properly aligned.
  • Address manufacturing defects: Consult a mechanic or the manufacturer if you suspect a defect in any engine components.

What to Do if You Find Metal Shavings in Your Oil

Initial Steps

  • Assess the issue: Determine the severity of the problem by examining the size, shape, and quantity of metal shavings.
  • Consult a mechanic: Seek professional advice to diagnose and address the underlying cause.

Potential Repairs and Solutions

  •  Flush the engine: Remove contaminated oil and clean the system.
  •  Replace damaged components: Repair or replace any damaged engine parts.
  •  Rebuild or replace the engine: A complete engine rebuild or replacement may be necessary in extreme cases.


Vigilance in car maintenance, recognizing the causes of metal shavings in oil, and addressing issues promptly can help ensure a well-functioning and long-lasting engine. Regular maintenance and inspections play a crucial role in preventing severe engine damage and keeping your vehicle running smoothly.