What Size Is a Standard Oil Drain Plug?

There isn’t a single “standard” size for oil drain plugs. Most modern passenger cars use a metric M14 × 1.5 thread, but other common sizes include M12 × 1.5 (or 1.25), M16 × 1.5, and, less often, SAE threads like 1/2-20. The correct size varies by make, model, engine, and oil pan material, so verify in your owner’s manual or parts catalog before buying tools or replacement parts.

Why There Isn’t One Universal Size

Automakers design oil pans and drain plugs to fit different engines, packaging constraints, and materials (aluminum vs. steel). Over time, most manufacturers standardized on metric threads, but the specific diameter and pitch still vary. Some older North American vehicles and certain aftermarket pans may retain SAE (inch) threads.

Common Oil Drain Plug Thread Sizes

The list below outlines the thread sizes you’re most likely to encounter and the types of applications where they appear. Thread size refers to the plug’s diameter and pitch, not the socket size used to remove it.

• M14 × 1.5: Very common on late-model passenger vehicles across many brands.
• M12 × 1.5 (or M12 × 1.25): Found on smaller engines and some Asian makes/models.
• M16 × 1.5: Used on some larger engines, SUVs, and European applications.
• M18 × 1.5: Less common; appears on larger truck/diesel applications.
• SAE 1/2-20 UNF or 5/8-18 UNF: Seen on some older American vehicles and certain aftermarket or performance oil pans.

While M14 × 1.5 is a frequent match, always confirm thread diameter and pitch; guessing based on vehicle origin or plug head size can lead to cross-threading or leaks.

How to Identify Your Exact Drain Plug Size

Use the steps below to determine the correct drain plug for your vehicle with confidence and without risking damage.

1. Check official sources: Your owner’s manual, factory service manual, or OEM parts catalog (via VIN) often lists the drain plug part number and washer size.
2. Use reputable parts catalogs: Look up your year/make/model on OEM or trusted aftermarket sites; cross-check part numbers and listed thread size/pitch.
3. Measure directly: If the plug is out, use a caliper for diameter and a thread pitch gauge to confirm metric pitch (e.g., 1.5 mm) or UNF pitch (e.g., 20 TPI).
4. Do not rely on socket size: The hex head (e.g., 14, 17, or 19 mm) does not indicate the thread size or pitch.
5. If threads are damaged: Verify whether you need an oversized repair plug or a thread repair insert (Heli-Coil/Time-Sert) matched to the original spec.

Verifying before you buy avoids mismatches that can strip an oil pan—especially common with aluminum pans.

Typical Wrench/Driver Sizes for Drain Plugs

These are the common head types and wrench/driver sizes you might need to remove a drain plug; the head type can vary even when the thread size is the same.

• External hex: 13, 14, 15, 17, or 19 mm sockets are common.
• Internal hex (Allen): 6, 8, or 10 mm on some European and performance applications.
• Torx/internal drive: T45 or T50 appear on a few models.

Confirm the head type before service to avoid rounding fasteners; a six-point socket and a torque wrench are recommended.

Crush Washers and Sealing Gaskets

Most oil drain plugs use a replaceable sealing washer. Correct washer size and material are essential to prevent leaks.

• Aluminum crush washers: Common for M12, M14, and M16 plugs (match the inner diameter to the plug size, e.g., 14 mm ID for M14).
• Copper washers: Reusable a limited number of times; often annealed to restore softness.
• Fiber/nylon washers: Used on some applications; torque sensitivities vary.
• Captive/sealed plugs: Some plugs include an integrated washer or bonded rubber seal—replace the entire plug if specified by the manufacturer.

Always match the washer to the plug size and follow the torque spec; a new crush washer is inexpensive insurance against seepage.

Torque Guidelines (Always Verify for Your Vehicle)

Factory torque specs vary by engine, pan material, and plug design. The ranges below are typical, but you should defer to the service manual when available.

• M12 plugs: approximately 20–30 Nm (15–22 ft-lb)
• M14 plugs: approximately 25–40 Nm (18–30 ft-lb)
• M16 plugs: approximately 30–45 Nm (22–33 ft-lb)

If your oil pan is aluminum, stay toward the lower end of the range unless the manufacturer states otherwise. Over-tightening can strip threads or deform the sealing surface.

When to Consider Replacement or Repair

If the plug or pan threads are worn, you have several options depending on the condition and the vehicle’s requirements.

• New OEM or quality aftermarket plug matched to the specified thread size and pitch.
• Magnetic drain plug (same spec) to help capture ferrous particles during service.
• Oversize/self-tapping repair plug as a temporary fix only if the original threads are compromised.
• Thread repair insert (Heli-Coil/Time-Sert) for a durable, permanent restoration to the original size.

Permanent thread repair with an insert is generally preferred to oversized plugs, especially on aluminum pans where long-term sealing and serviceability matter.

Bottom Line

There’s no single standard oil drain plug size, but M14 × 1.5 is the most common on late-model cars. Other frequent sizes include M12 × 1.5 (or 1.25) and M16 × 1.5, with occasional SAE threads on older or specialized applications. Confirm via manual or measurement, use the correct washer, and torque to spec to avoid leaks and damage.

Summary

Most vehicles today use a metric oil drain plug, commonly M14 × 1.5, but sizes vary by model. Identify your exact thread size and pitch through official documentation or precise measurement, don’t confuse socket size with thread size, replace the crush washer, and torque correctly—especially on aluminum pans. Proper identification and installation prevent stripped threads and oil leaks.

What socket size do I need for an oil change?

You need a socket wrench (14mm or 15mm), an oil filter wrench, an oil drain pan, a funnel, and a new oil filter.

What size socket do I need to remove a drain plug?

As others have said, a 12 or 8 point (divisible by 4) will work to get in there. If a specific wrench size fits, it requires a larger sized socket to fit said fastener. It might require a 1/2”-11/16” socket to fit over the flats and bite on the corners of the plug.

Is an oil drain plug universal?

Let’s get one thing straight: oil drain plugs are not universal. Just because an oil drain plug has the thread pitch you need for a vehicle, that doesn’t mean it will work with the oil drain pan. Here’s what you need to know about oil drain plugs and gaskets so you can select the right replacements.

What size do I need for an oil drain plug?

What size wrench to use for an oil drain plug depends on the size of the oil drain plug itself, which is a long bolt head. There is no universal oil plug size, but they do come in just a few several standard sizes, such as ¼ inch (. 6 centimeters), 3/8 inch (. 9 centimeters), ½ inch (1.3 centimeters), etc.