Choosing the Right Crush Washer: A Guide to M14 and M18 Aluminum Drain Plug Washers

When it comes to routine engine maintenance, a reliable seal on your oil drain plug is critical—and that’s where the crush washer comes in. Often underestimated, this small ring prevents oil leaks and ensures your oil pan stays sealed tight. Whether you're shopping for an M14 aluminum crush washer, a M14 oil drain plug washer, or stepping up to an M18 aluminum crush washer, knowing the right type and size for your vehicle is key.

In this article, we'll cover the purpose and advantages of aluminum crush washers, explore the common M14 drain plug washer, and explain where to buy quality replacements like the M14 crush washer AutoZone offers.

Understanding the Purpose of a Crush Washer

A crush washer is a soft metal ring—usually made from aluminum or copper—that sits between the oil drain plug and the oil pan. As the plug is tightened, the washer compresses slightly, creating a tight, leak-proof seal. The soft metal fills in any imperfections on the mating surfaces, which is why it’s so effective.

The most common sizes used in vehicles are M14 and M18, referring to the thread diameter in millimeters of the oil drain bolt.

The M14 oil drain plug washer is commonly used in many Japanese, European, and some domestic vehicles.

The M18 aluminum crush washer is typically found in larger vehicles or heavy-duty applications where a larger plug is needed to accommodate higher oil flow or volume.

These washers are generally considered single-use items. Once crushed, they don’t rebound, which means they won't seal properly if reused. Replacing your crush washer every oil change is a best practice and an inexpensive way to avoid oil leaks.

M14 Aluminum Crush Washer: The Most Popular Size

The M14 aluminum crush washer is one of the most frequently used washers in the automotive world. Its popularity comes from its compatibility with a wide range of cars and its ability to form a dependable seal thanks to the softness of aluminum.

Benefits of Aluminum Crush Washers:

Lightweight and corrosion-resistant

Soft enough to deform and seal tightly

Durable under high temperature and pressure

Compatible with both steel and aluminum oil pans

M14 Drain Plug Washer vs. Generic Washers
Although generic drain plug washers may appear similar, only an M14 drain plug washer is precision-sized for a 14mm drain bolt. Using a washer that’s slightly off in size can lead to leaks or cross-threading.

When shopping for these washers, you may see them labeled as:

M14 oil drain plug washer

M14 aluminum crush washer

14mm crush washer

They are all functionally the same but may vary slightly in thickness or inner/outer diameter depending on the brand or manufacturer. Always check your vehicle’s specifications or consult the owner's manual for exact sizing.

Where to Buy: M14 Crush Washer AutoZone and More

If you're looking for reliable and convenient access to crush washers, retail chains like AutoZone offer a wide variety of options, including the M14 crush washer AutoZone supplies in-store and online. These washers are typically sold individually or in value packs of 5–10, making them easy to keep on hand for future oil changes.

Advantages of Buying from AutoZone:

Access to name-brand and OEM-compatible parts

Clear labeling for size and material (e.g., aluminum or copper)

Availability of multi-packs for frequent DIYers

Staff support for confirming compatibility with your vehicle

When browsing AutoZone or similar stores, ensure you're selecting the correct material and size. For example, you may find both M14 aluminum crush washers and M14 copper washers—both work well, but aluminum is more common and often recommended for aluminum oil pans.

What About the M18 Aluminum Crush Washer?

For those with vehicles requiring a larger drain bolt, the M18 aluminum crush washer offers the same leak-proof performance on a larger scale. These are typically used in trucks, performance vehicles, and some European models.

Before purchasing, always confirm:

Thread size (e.g., M14 or M18)

Washer material (aluminum for standard use, copper for higher durability)

Outer diameter clearance (some oil pan designs have recesses or narrow sealing surfaces)

If you’re unsure of the size, online lookup tools on sites like AutoZone or manufacturer websites can match washers based on your vehicle make and model.

The M14 aluminum crush washer, M14 oil drain plug washer, and M18 aluminum crush washer may seem like minor details, but they’re essential for a secure and leak-free oil change. Replacing your M14 drain plug washer with every oil change is a smart and inexpensive habit that protects your engine over time.

Whether you pick up your M14 crush washer at AutoZone or from another trusted retailer, be sure to choose the right size and material for your vehicle. That little ring of metal could be the barrier between a clean, well-maintained engine and an unexpected oil leak.