Why Crush Washers Matter: The Small Seal That Keeps Oil In and Problems Out

When it comes to vehicle maintenance, some parts are easy to overlook—until they fail. One such component is the drain bolt crush washer. This small, inexpensive part plays a crucial role in sealing your engine’s oil drain plug and preventing leaks after an oil change. Whether you're using an aluminum drain plug washer or a specific size like a crush washer M12 or crush washer M14, knowing the right type and how to replace it can save you from costly engine damage.

In this article, we'll explore the purpose of crush washers, how to choose the right size, and why places like Advance Auto Parts are a go-to source for a quality car drain plug washer.

What Is a Drain Bolt Crush Washer, and Why Is It Important?

A drain bolt crush washer is a soft metal ring—usually made of aluminum or copper—that’s placed between the oil drain bolt and the oil pan. When the bolt is tightened, the washer compresses to form a tight seal. This prevents oil from seeping out under pressure and ensures a leak-free oil change.

Key Functions of a Crush Washer:

Seals the oil pan opening to prevent leaks

Distributes bolt torque evenly to prevent damage to the oil pan

Compensates for surface imperfections on metal mating surfaces

Over time, the washer deforms and hardens, losing its ability to create a proper seal. That’s why mechanics always recommend replacing the crush washer every time you change your oil—even if the old one “looks fine.”

Choosing the Right Size: Crush Washer M12, Crush Washer M14, and More

Crush washers are not one-size-fits-all. The size depends on the thread size of your oil drain plug. Two of the most common sizes found in vehicles are:

Crush washer M12: For drain bolts with 12mm threads

Crush washer M14: For drain bolts with 14mm threads

Using the wrong size can lead to oil leaks or stripped threads. If the washer is too small, it won’t fit over the bolt; too large, and it won’t seal properly. When in doubt, check your vehicle’s service manual or consult your parts supplier.

Another helpful resource is Advance Auto Parts, which carries a wide variety of crush washers for nearly every make and model. Many listings will specify whether the washer is compatible with specific drain plug sizes or vehicle models.

Material Matters: Why an Aluminum Drain Plug Washer is Common—and When to Use Other Types

Most factory-installed car drain plug washers are made from aluminum. This soft, malleable metal offers several benefits:

Pros of Aluminum Drain Plug Washers:

Excellent sealing properties

Lightweight and corrosion-resistant

Affordable and widely available

Aluminum works particularly well with aluminum oil pans, preventing galvanic corrosion between dissimilar metals. However, some vehicles use copper or even composite washers for higher heat resistance or durability.

If your car originally came with an aluminum drain plug washer, stick with the same material unless otherwise advised by the manufacturer. Mixing materials can sometimes lead to poor sealing or long-term compatibility issues.

Where to Buy: Crush Washer Advance Auto Parts and Other Reliable Sources

When shopping for a car drain plug washer, it’s important to buy from a reputable source. Big-name retailers like Advance Auto Parts stock genuine OEM-style washers as well as universal options.

Why Buy from Advance Auto Parts?

Guaranteed fit by make/model

Availability of multi-packs for DIY oil changers

Access to both metric (M12, M14) and SAE sizes

Trustworthy customer reviews and staff guidance

Whether you’re doing an oil change on your own or stocking up for future maintenance, keeping a few spare crush washers in your garage is a smart move.

Don’t Overlook the Crush Washer

The drain bolt crush washer may be one of the smallest components in your engine, but it plays an outsized role in maintaining proper oil pressure and preventing leaks. Whether you’re working with a crush washer M12, a crush washer M14, or an aluminum drain plug washer, always replace it during oil changes.

It’s a minor expense that can prevent major problems.

Quick Tips:

Never reuse a crush washer

Always match the size and material to your vehicle specs

Tighten the drain plug to the manufacturer’s torque rating to avoid crushing the washer too much

Buy in bulk from suppliers like Advance Auto Parts for convenience