What Size Is the Bolt for the Oil Pan?

It depends on the vehicle. For most passenger cars, the oil drain plug (the “bolt” you remove to change oil) is typically M12x1.25, M12x1.5, or M14x1.5 with a 14–17 mm hex head, while the oil pan mounting/perimeter bolts are usually M6 or M8 with 10–13 mm heads. Exact size varies by make, model, engine, and pan material—always verify with your owner’s manual or by measuring the threads.

What You Might Mean: Drain Plug vs. Oil Pan Bolts

When people ask for the “oil pan bolt size,” they usually mean the oil drain plug. That’s the removable plug at the bottom of the pan used to drain engine oil. The oil pan itself is also fastened to the engine block with a series of smaller perimeter bolts. These are different parts with different sizes and torque requirements.

Oil Drain Plug

The drain plug’s size is defined by its thread diameter and pitch (for example, M14x1.5) and typically has a 14–17 mm hex head. It also seals with a gasket or crush washer that must match the plug’s size and style.

Oil Pan Perimeter Bolts

These are smaller fasteners (commonly M6x1.0 or M8x1.25) holding the pan to the engine block. They have much lower torque specs than the drain plug and are not removed during routine oil changes.

Common Oil Drain Plug Sizes by Make

The following are typical patterns seen across popular brands. Variations exist within each brand by engine family and model year, so use this as a starting point—not a guarantee.

• Toyota/Lexus: Frequently M12x1.25 (14 mm hex head) on many cars; some trucks/SUVs use M14x1.5.
• Honda/Acura: Commonly M14x1.5 (often 17 mm hex head).
• Nissan/Infiniti: Often M12x1.25 (14 mm hex head); some models use M14x1.5.
• Mazda: Typically M14x1.5 on many models; some M12x1.25.
• Subaru: Many use a larger M20x1.5 drain plug (17 mm hex head) with a 20 mm crush washer; some newer engines vary.
• Hyundai/Kia: Commonly M14x1.5.
• Ford/Lincoln: Frequently M14x1.5; some newer models use replaceable plastic drain plugs (size differs and is model-specific).
• GM (Chevrolet, GMC, Buick, Cadillac): Often M14x1.5 or M12x1.75 depending on engine family.
• Volkswagen/Audi: Commonly M14x1.5 on many gasoline engines; always verify by engine code.
• BMW/MINI: Often M12x1.5 or M14x1.5; some models use composite pans and specific OE plugs with lower torque.
• Mercedes-Benz: Frequently M14x1.5 on models with a drain plug; some engines are designed to be serviced via top-side extraction.
• Chrysler/Dodge/Jeep/Ram: Commonly M14x1.5 on late-model V6/V8; older engines may differ.

These patterns cover a large portion of the market, but outliers exist. Always confirm via the service manual or by measuring your plug to avoid cross-threading or leaks.

Typical Sizes for Oil Pan Perimeter Bolts

Oil pan mounting bolts are smaller and numerous, designed to evenly clamp the pan and gasket without warping. They are not the same as the drain plug and are usually removed only for pan service.

• M6x1.0 (common; 10 mm hex head) with torque usually around 8–12 N·m (71–106 in-lb).
• M8x1.25 (less common; 12–13 mm hex head) with torque usually around 18–25 N·m (13–18 ft-lb).

Because these fasteners thread into aluminum or cast alloy surfaces on many engines, proper torque and tightening sequence are critical to prevent warping or stripped threads.

How to Identify Your Exact Size

If you don’t have the manual, you can still determine the correct size and pitch using basic tools and references.

1. Check the owner’s or factory service manual for the drain plug size, washer type, and torque spec.
2. Look up the OEM drain plug part number by VIN on the automaker’s parts catalog; the listing often shows thread size and washer spec.
3. Measure the old plug with calipers: thread diameter (e.g., ~12 mm or ~14 mm) and length under the head.
4. Determine thread pitch: use a metric pitch gauge or measure threads over a known distance (common pitches are 1.25, 1.5, and 1.75 mm).
5. Match the washer: aluminum, copper, or bonded rubber crush washer must match plug size (e.g., 12 mm, 14 mm, 20 mm ID).
6. Test fit gently by hand only; it should thread smoothly without resistance. Never force it—cross-threading will damage the pan.

Verifying size and pitch before installation helps ensure proper sealing, prevents thread damage, and avoids leaks.

Typical Torque Ranges and Cautions

Torque varies by thread size, plug design, and pan material. When the exact spec is unavailable, the following ranges are common—not definitive:

• M12 drain plug: roughly 25–35 ft-lb (34–47 N·m).
• M14 drain plug: roughly 30–40 ft-lb (40–54 N·m).
• Larger plugs (e.g., M20 used by some Subaru engines): roughly 25–33 ft-lb (34–45 N·m), often lower due to large sealing area.
• Composite/plastic pans or plastic drain plugs: significantly lower torque; follow OE spec strictly.

Always favor the manufacturer’s torque spec. Over-tightening can crush washers improperly, crack aluminum or composite pans, or strip threads.

Washer Types and Best Practices

The sealing washer is as important as the bolt. Using the wrong washer or reusing a spent one is a common source of leaks.

• Crush washers (aluminum or copper): designed for one-time use; replace at each oil change.
• Bonded rubber/metal washers: model-specific; torque carefully to avoid extruding the rubber.
• Magnetic plugs: interchangeable with the correct thread/pitch; do not change torque values unless specified.

Matching the correct washer to the plug and applying the proper torque is essential for a leak-free seal.

Stripped Threads or Damaged Plugs

If threads are damaged, there are safe repair options that preserve the pan.

• Oversize/self-tapping drain plugs: temporary solution; use with caution.
• Thread repair inserts (Heli-Coil/Time-Sert): permanent, professional-grade fix that restores original size and torque spec.
• Pan replacement: last resort when damage is extensive or on thin composite pans.

Choosing the right repair depends on pan material and damage severity; thread inserts are the preferred long-term solution.

Help Me Pinpoint Your Exact Bolt Size

Provide a few details and I can give you the precise size, washer, and torque spec for your vehicle.

• Year, make, and model (e.g., 2018 Honda Accord).
• Engine size/code (e.g., 2.0T, 5.3L V8).
• Whether you mean the drain plug or the perimeter pan bolts.
• Any known modifications (aftermarket pan, magnetic plug kit, etc.).

With that information, I can confirm the thread size and pitch, the correct washer, and the official torque specification.

Summary

There isn’t a single “oil pan bolt” size. Most passenger vehicles use an M12 or M14 drain plug with a 14–17 mm hex head and a matching crush washer, while oil pan perimeter bolts are commonly M6 or M8 with low torque. To avoid leaks or damage, verify your exact size and torque in the service manual or by measuring the existing plug—and replace the washer at every oil change. If you share your vehicle details, I can provide the exact specification.