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Copper vs Aluminium Crush Washer – What’s the Difference

Copper vs Aluminium Crush Washer

A crush washer is a small, flat ring used to ensure proper sealing of fluid systems. It is most commonly found in automotive applications for oil and fuel systems, where it is positioned between a bolt and a fitting to obtain a tight seal. When you need to replace your old and worn-out washer, you generally have two options: copper or aluminium. Both materials have pros and cons, making it difficult to determine the best choice. This blog compares copper and aluminium crush washers to help you choose the best.

What is Copper Crush Washers?

Copper is a common choice for crush washers because it is affordable and malleable, making it easy to form into an effective seal. Copper is also an excellent conductor of heat, which will help dissipate heat away from the engine. However, copper is relatively soft, which can degrade and deform over time, leaving your fluid system vulnerable to leakage.

What is Aluminium Crush Washers?

Aluminium is another popular choice for crush washers because it is lightweight, corrosion-resistant, and easy to manufacture. It also has a high strength-to-weight ratio, which means it can handle heavy loads while remaining light. However, copper is more malleable than aluminium, making it slightly more difficult to achieve a tight seal. Additionally, aluminium crush washers may not be suitable for high-temperature applications as they tend to degrade at high temperatures.

Difference Between Copper and Aluminium Crush Washers

Application-Specific Considerations

When determining which material to use, you need to consider the specific requirements of your application. For instance, copper may be the better choice to conduct heat away from the engine, while aluminium may be preferred if you require a high strength-to-weight ratio. Alternatively, you may need a copper crush washer with brake or power steering fluid or an aluminium crush washer for oil filters or coolers.

Importance of correct installation

Regardless of the material, installing the correct crush washer correctly is crucial. Proper installation ensures a tight and effective seal, reducing the risk of leaks. Over-tightening a crush washer can cause it to deform or rupture, while under-tightening it can leave gaps, causing leaks. Always follow the manufacturer’s instructions when installing your crush washer to ensure the best results.


In summary, there is no definitive answer to whether copper or aluminium crush washers are better, as it depends on your application-specific needs. While copper is more malleable and better at conducting heat, aluminium is lightweight and corrosion-resistant, making it suitable for high-stress applications. Proper installation is also vital to ensure that either material provides an effective seal. Consult a professional to determine the ideal crush washer for your unique application to achieve optimal performance and longevity.

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