The Essential Guide to Crush Washers: Sealing Your Oil Drain Plug the Right Way

When performing an oil change, many DIYers and even professionals overlook a small but critical component—the drain plug washer. This simple ring-shaped part provides the seal that prevents oil leaks once the plug is reinstalled. Whether you drive a sedan, SUV, or performance car, using the correct crush washer is vital for a proper oil change. In this article, we’ll explore types like the crush washer M12, crush washer M14, and aluminum drain plug washers, and explain where to find them—including options at places like Advance Auto Parts.

What Is a Drain Plug Crush Washer?

A drain plug crush washer (also known as an oil plug washer or oil drain gasket) is used to seal the oil drain bolt against the oil pan. Unlike standard flat washers, a crush washer is designed to deform slightly under torque, filling any microscopic gaps and creating a tight, leak-free seal.

Crush washers are often made from soft metals like aluminum or copper. This allows them to compress without damaging the oil pan or the car drain plug washer surface. Some vehicles even require a specific washer size or material to match the manufacturer's torque specs and sealing surfaces.

Choosing the Right Size: M12 and M14 Crush Washers

If you're replacing your oil, it's crucial to match the crush washer to the size of your oil drain bolt.

Crush Washer M12

A crush washer M12 fits drain bolts with a 12mm diameter. This size is common in many Japanese and Korean vehicles, including Toyota, Honda, and Hyundai. Always check your owner's manual or measure your drain bolt before selecting a washer.

Crush Washer M14

A crush washer M14 fits a 14mm bolt and is frequently used in European and American vehicles. Many BMW, Volkswagen, and GM models use M14 bolts, and using the correct washer ensures the plug torques properly without stripping or leaking.

Tip: The “M” size refers to the diameter of the bolt, not the outside diameter of the washer—so choose carefully based on your drain bolt, not the oil pan hole size.

Materials Matter: Why Use an Aluminum Drain Plug Washer?

There are several materials available for crush washers, but aluminum drain plug washers are among the most popular—and for good reason.

Advantages of aluminum washers:

Soft enough to crush and form a tight seal

Corrosion-resistant

Matches many OEM specifications

Less likely to damage threads or pan surface

In contrast, copper washers are also common and offer slightly better thermal conductivity, but they may require higher torque and are sometimes reused (even though that’s not recommended). Nylon or rubber washers are often found on aftermarket car drain plug washers, but may not hold up under extreme heat.

If your vehicle originally came with an aluminum washer, it’s best to stick with the same material to maintain the proper seal and bolt torque.

Where to Find the Right Crush Washer

You don’t have to look far to find the proper crush washer for your car. Major retailers like Advance Auto Parts carry a wide range of crush washers, including M12 and M14 sizes, in both copper and aluminum.

When shopping, make sure to:

Match the washer to your drain bolt size (M12, M14, etc.)

Choose the correct material (aluminum, copper, etc.)

Avoid reusing old washers, even if they “look okay”

Some oil change kits include washers, but if you're sourcing them separately, it's always a good idea to buy a few extras.

Pro Tip: If your oil plug requires a gasket and doesn’t have one—or if you reuse a deformed washer—it could result in a slow leak that goes unnoticed until it causes major engine issues. Spending a dollar or two on a new drain bolt crush washer could save hundreds in repairs.

While often overlooked, the drain plug crush washer is a key player in your vehicle's oil system. Whether you're replacing a crush washer M12 on your Honda or upgrading to an aluminum drain plug washer on your BMW, always use the correct size and material. Stores like Advance Auto Parts make it easy to find replacements, and using the right car drain plug washer ensures leak-free, stress-free maintenance.