Why Do Chainsaws Leak Oil? A Comprehensive Guide

Chainsaws are versatile tools, used by both professionals and hobbyists for a myriad of cutting tasks. One common concern that many chainsaw owners face is oil leakage.

Chainsaw oil leakage can occur when air replaces the space previously occupied by the oil as it is pumped from the tank to the guide bar.

This article aims to provide a detailed understanding of chainsaw oil and the reasons behind its leakage. By the end, you’ll have a clearer picture of why do chainsaws leak oil and what you can do about it.

Understanding Chainsaw Oil

Before delving into the reasons for oil leaks, it’s important to understand what chainsaw oil is and why it’s crucial.

1. The Role of Chainsaw Oil

Chainsaw oil, or bar and chain oil, plays an essential role in ensuring the smooth operation of your chainsaw. It primarily serves to:

  • Reduce friction between the chain and the guide bar.
  • Prevent premature wear and tear of the chain.
  • Disperse heat generated during the cutting process.

2. Types of Chainsaw Oil

There are mainly two types of chainsaw oil:

  • Winter oil: This is thinner and is used during colder months to maintain fluidity.
  • Summer oil: This is thicker and used in warmer weather to ensure optimal lubrication.

Why Do Chainsaws Leak Oil? Most Common Causes

Now that we understand the role and types of chainsaw oil, let’s explore the most common causes of chainsaw oil leakage. These leaks can stem from several factors, each with their own implications and solutions.

1. Faulty Oil Cap

The oil reservoir cap may not be properly sealed, which can cause leaks. Over time, caps can become worn out or might not be screwed on tightly.

2. Damaged Oil Lines

Oil lines, which transport oil from the reservoir to the bar, can get damaged, leading to leaks. These lines can deteriorate with age or get punctured by debris.

3. Overflow of Reservoir

Overfilling the oil reservoir can lead to spillage, especially when the chainsaw is in use.

4. Malfunctioning Oil Pump

A defective oil pump might pump out more oil than necessary, causing an overflow. Conversely, it might not pump out enough oil, causing the reservoir to get pressurized and leak.

5. Poor Quality or Wrong Type of Oil

Using the wrong type of oil for the weather conditions or low-quality oil can cause it to seep out more readily.

How to Fix Chainsaw Oil Leaks – Effective Solutions

Fixing chainsaw oil leaks largely depends on the underlying cause. Here are some potential solutions:

1. Replace the Oil Cap

A worn-out oil cap is an easy fix. Simply purchase a new oil cap compatible with your chainsaw model and replace the old one. Be sure to screw it on tightly to prevent future leaks.

2. Inspect and Replace Damaged Oil Lines

Inspect oil lines regularly for any signs of wear, tear, or damage. If you notice any punctures or cracks, replace the oil lines with new ones. Regular maintenance can prevent potential oil leaks.

3. Avoid Overfilling the Reservoir

Always check the oil level in the reservoir before use. Avoid overfilling as this can lead to unnecessary spillage.

4. Repair or Replace the Oil Pump

If you suspect a malfunctioning oil pump, it’s best to take your chainsaw to a professional for diagnosis and repair. If the oil pump is beyond repair, you may need to purchase a new one.

5. Use the Correct and High-Quality Oil

Always use the right type of oil for the current weather conditions. Moreover, opt for high-quality oils as they are less prone to leakage compared to their low-quality counterparts.

Regular chainsaw maintenance and timely repairs can prevent oil leaks and extend the life of your chainsaw, ensuring its optimal performance.

Why does my chainsaw leak oil when sitting? Expert Reasons and Solutions

Even when not in use, your chainsaw may still leak oil. This can be perplexing, but there are expert reasons for this phenomenon.

1. Residual Oil in the Oil Pump or Guide Bar

Even after usage, some oil might still be present in the oil pump or the guide bar. This oil can slowly seep out, appearing as a leak when your chainsaw is sitting.

2. Faulty Seals or Gaskets

Damaged seals or gaskets in the oil tank can lead to slow leaks. This is usually a sign of wear and tear and will need replacement to prevent further leakage.

3. Temperature Changes

Fluctuations in temperature can cause the oil to expand and contract. This can lead to leaks especially when the chainsaw is stored in an area with varying temperatures.

4. Poor Storage Practices

Incorrect storage, such as storing the chainsaw on its side or not cleaning it properly before storage, can also result in oil leaks.

Expert Solutions to Chainsaw Oil Leaking When Sitting

Finding a puddle of oil under your chainsaw while it’s not in use can be disconcerting. But by identifying the cause, you can implement the right solution. Here are some expert solutions to common reasons for oil leakage in idle chainsaws:

1. Clear Residual Oil

Always run your chainsaw dry before storing it. You can do this by operating the chainsaw without cutting anything until it runs out of oil. This can help clear any residual oil in the oil pump or guide bar and prevent leakage.

2. Replace Faulty Seals and Gaskets

If you notice worn-out seals or gaskets, it’s time for a replacement. You can either do this yourself or take your chainsaw to a professional. Regular checks can help spot faulty seals before they cause major leaks.

3. Store in a Stable Temperature

Try to store your chainsaw in an area with stable temperatures to prevent oil expansion and contraction. This could be a shed, a garage, or any other area that does not experience drastic temperature changes.

4. Correct Storage Practices

Store your chainsaw properly by cleaning it thoroughly before storage and placing it in an upright position. This not only prevents oil leakage but also prolongs the life of your chainsaw.

Is it normal for a chainsaw to leak oil?

  • Yes, it is relatively normal for chainsaws to leak oil.
  • Chainsaws are designed with an automatic oiling system that lubricates the chain and guide bar during operation.
  • When the chainsaw is not in use, residual oil in the system can slowly seep out.
  • This is particularly common in chainsaws with an automatic oiling system that doesn’t have a valve to stop the oil flow when the chainsaw is idle.


In conclusion, oil leakage in chainsaws can be a common occurrence due to various reasons, including faulty components, improper usage or storage, and temperature changes. However, with regular maintenance and proper storage, these issues can be minimized.

I personally recommend always opting for high-quality oils and ensuring your chainsaw is stored in an upright position in a temperature-stable environment.


Can I use motor oil for my chainsaw?

While motor oil can be used as a temporary solution, it’s not recommended for long-term use. Chainsaw oil is specifically designed to cater to the needs of chainsaws.

How often should I refill chainsaw oil?

This depends on usage. Always check the oil level before starting your chainsaw. Typically, when you refill the fuel tank, it’s a good time to top up the oil.

Are Stihl chainsaws supposed to leak oil?

This condition is considered typical for any chainsaw equipped with a comparable bar and chain lubrication system.

Can a chainsaw function without oil?

While a chainsaw can operate without oil, it’s not recommended as it will lead to increased friction, heat, and premature wear of the chain.

What is the most common cause of an oil leak?

The most common cause of an oil leak in chainsaws is typically due to worn-out or damaged seals, gaskets, and oil lines. Regular checks and maintenance can help prevent these issues.

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