What Size Bolt Is the Oil Drain Plug?

It depends on the vehicle: most modern passenger cars use an M14 x 1.5 drain plug, but other common sizes include M12 x 1.25, M12 x 1.75, M16 x 1.5, and M20 x 1.5, with hex-head sizes typically between 13 mm and 19 mm. Because sizes vary by make, model, engine, and even model year, the exact specification should be verified in your owner’s manual or an OEM parts catalog.

Why There Isn’t One Universal Size

Oil drain plugs are sized to the oil pan’s threaded bung, which varies across manufacturers and engines. Even within a brand, different engines, materials (steel vs. aluminum pans), and design changes across model years produce different thread sizes, thread pitches, and head styles. That’s why relying on a single “standard” can lead to cross-threading, leaks, or stripped pans.

Common Oil Drain Plug Sizes

These are the thread sizes most frequently encountered on passenger vehicles. Use them as a starting point when checking your specific application, but always confirm before buying or installing a plug.

• M12 x 1.25 (fine pitch, common on some Japanese makes and older models)
• M12 x 1.75 (coarser pitch, seen on select applications)
• M14 x 1.5 (very common across many brands and engines)
• M16 x 1.5 (used on some larger engines and trucks)
• M18 x 1.5 (less common but present on select European and truck applications)
• M20 x 1.5 (common on some Subaru and larger-displacement engines)
• SAE/Imperial examples: 1/2″-20 UNF, 5/8″-18 UNF (found on some older American vehicles and certain trucks)

While these sizes cover the majority of cases, exceptions exist, and plug design can differ (magnetic tips, captive/plastic plugs for composite pans, or internal-hex heads), reinforcing the need to verify your exact fit.

Typical Hex/Tool Sizes for Drain Plugs

The bolt head or drive interface also varies. Below are common wrench or driver sizes you might encounter.

• External hex: 13 mm, 14 mm, 15 mm, 17 mm, 19 mm
• Internal hex (Allen): 6 mm, 8 mm
• Square drive: accepts 3/8″ or 1/2″ ratchet directly (no socket)

The head size does not determine the thread size; it only tells you which tool fits. Always match the thread diameter and pitch to your oil pan.

How to Find the Exact Size for Your Vehicle

Use the steps below to identify your drain plug size accurately and avoid damaging the oil pan.

1. Check the owner’s manual or service manual: Some list the drain plug and washer size and torque spec.
2. Look up your VIN in an OEM parts catalog: Dealer sites and reputable online catalogs will return the exact plug part number and size.
3. Consult a manufacturer-specific parts diagram: Cross-reference the plug and crush washer part numbers for size clues (e.g., 14 mm washer typically indicates an M14 plug).
4. Measure with calipers and a thread pitch gauge: Major diameter identifies M12/M14/M16/M20; pitch gauge confirms 1.25/1.5/1.75 mm. For SAE, measure diameter (e.g., ~0.500″ or ~0.625″) and threads-per-inch (TPI).
5. Bring the plug to the parts counter: Matching against thread checkers is a quick, low-risk way to confirm.
6. Avoid “close enough” fits: If the plug doesn’t thread in smoothly by hand, stop—wrong pitch or diameter can strip the pan.

Following these steps ensures you get an exact match, which is essential for sealing, torque accuracy, and long-term pan integrity.

Typical Torque Specs and Washer Types

Correct torque and the right sealing washer are as important as thread size. Below are general ranges; always prioritize your vehicle’s official spec.

• M12 plugs: approximately 20–25 lb-ft (27–34 N·m)
• M14 plugs: approximately 25–30 lb-ft (34–41 N·m)
• M16 plugs: approximately 30–35 lb-ft (40–47 N·m)
• M20 plugs: approximately 35–40 lb-ft (47–54 N·m)

These ranges are typical, but pan material and washer type can alter requirements. Over-tightening, especially on aluminum pans, can cause costly damage.

Common Washer/Seal Types

The sealing interface varies by design. Here are the most common washer types and when they’re used.

• Aluminum crush washer: single-use, common on Japanese and European cars
• Copper crush washer: single-use, often preferred for high-temperature cycling
• Fiber or composite washer: used on select applications, sometimes reusable
• Integrated captive seal (often on plastic/composite pans): plug must be replaced each service

Using the correct washer—and replacing single-use types every oil change—prevents drips and reduces the risk of overtightening to “stop a leak.”

Brand and Vehicle Family Tendencies (Verify for Your VIN)

The examples below reflect common patterns, not guarantees. Always confirm for your exact engine and model year.

• Honda/Acura: Frequently M14 x 1.5 with a 17 mm hex; aluminum crush washer (14 mm ID) is typical.
• Toyota/Lexus/Scion: Commonly M14 x 1.5; some older 4-cyl engines use M12 x 1.25; many require a new aluminum washer each service.
• Nissan/Infiniti: Often M14 x 1.5; hex head commonly 14–17 mm depending on model/year.
• Subaru: Commonly M20 x 1.5 with a 17 mm hex; uses a 20 mm crush washer.
• Hyundai/Kia: Frequently M14 x 1.5 with 17 mm hex; verify on turbo and larger engines.
• Mazda: Often M14 x 1.5; aluminum washer recommended.
• VW/Audi: Frequently M14 x 1.5; some models use internal-hex plugs or single-use plastic/composite plugs with integrated seals.
• BMW/MINI: Commonly M12 x 1.5 or M14 x 1.5; some use internal-hex plugs; always check parts catalog for engine code.
• Mercedes-Benz: Typically M14 x 1.5 or M12 x 1.5; many models are serviced via top-side oil extraction but still have a pan plug.
• Ford/GM/Ram (light-duty): Mixed metric and SAE; M12 x 1.75 and M14 x 1.5 are common, with some older or truck applications using 1/2″-20 or 5/8″-18.

These tendencies can guide you toward likely sizes, but component changes within the same platform are not unusual, so a definitive check is still necessary.

Tools You’ll Likely Need

Having the right tools on hand helps prevent rounding fasteners or damaging threads.

• Metric socket set (13–19 mm) and/or appropriate Allen keys
• Torque wrench capable of 20–50 lb-ft (27–68 N·m)
• Calipers and a thread pitch gauge (for measurement/verification)
• New crush washer or the correct single-use plug (if required)
• Drain pan, gloves, and rags for cleanup

With these tools, you can remove, inspect, and reinstall or replace the plug to spec, ensuring a proper seal.

When to Replace and What to Watch For

Drain plugs and pans are durable, but certain conditions warrant replacement or extra care.

• Rounded or damaged hex head: replace the plug before it becomes immovable.
• Persistent seepage despite new washer and correct torque: check for pan damage or wrong washer type/size.
• Cross-threading or stripped pan threads: consider a thread repair (Time-Sert/Heli-Coil) rather than oversize “self-tapping” plugs.
• Plastic/composite plugs with integrated seals: replace at every oil service as specified by the manufacturer.
• Magnetic plugs: helpful for monitoring wear metals, but still require correct torque and sealing.

Addressing these issues promptly prevents larger repairs and helps maintain oil system integrity.

Summary

The oil drain plug size is vehicle-specific. While M14 x 1.5 is the most common on modern cars, many engines use M12, M16, or M20 metric plugs—and some older or truck applications use SAE threads. Confirm your exact size via the owner’s manual, an OEM parts catalog using your VIN, or precise measurement with calipers and a pitch gauge. Pair the correct plug with the proper crush washer and torque spec to ensure a reliable, leak-free seal.

What size bolt is used to change oil?

There isn’t a single “oil change bolt size” because sizes vary by vehicle. To find the correct size for your car, you must identify the specific drain plug bolt head size for your vehicle’s make and model. You can typically use a socket wrench set with common metric sizes like 14mm, 15mm, 17mm, or 19mm. If you don’t know the size, you can buy a vehicle-specific part or use a tool to measure the bolt, such as digital calipers, but a wrench that is too small can strip the head. 
How to Find the Right Size

1. Check Your Vehicle’s Owner’s Manual: Opens in new tabYour manual will often have the specific size of the drain plug. 
2. Consult an Auto Parts Store: Opens in new tabTell the store your vehicle’s year, make, and model, and they can look up the correct size. 
3. Measure the Bolt: Opens in new tabIf you have calipers or a ruler, you can measure the width of the bolt head to determine its diameter. 
4. Test Common Socket Sizes: Opens in new tabIf you don’t know the size, you may have to try the common metric socket sizes in the 14mm to 19mm range. 

Important Tips

• Use the Correct Tool: Use a socket or wrench that fits the bolt head snugly to avoid stripping it. 
• Replace the Washer: Always use a new crush washer when reinstalling the drain plug to prevent leaks. 
• Use a Proper Socket: For best results, use a 6-point socket, as these provide a more secure grip than 12-point sockets and reduce the risk of stripping. 

What size is the oil drain bolt?

Mild Steel M12 (12 mm) Oil Drain Bolt, Size: 15 mm.

What size socket do I need to remove the oil drain plug?

There isn’t a single socket size for all oil plugs; the correct size depends on your vehicle’s make, model, and year. Common sizes include 17mm and 14mm for many Japanese and European cars, but you might need to check your vehicle’s specifications or visit an auto parts store for help. A 6-point socket is recommended for better grip to avoid stripping the bolt head. 
How to find the right socket size

1. Check your vehicle’s manual: The most reliable way is to consult your car’s owner’s manual to find the specific drain plug size. 
2. Identify the head type: Most drain plugs have a hex-shaped bolt head. 
3. Measure the bolt head: If you have a socket set, try a few sizes to see which one fits snugly. 
4. Consult an auto parts store: Bring the vehicle information to an auto parts store, and they can look up the specific size for you. 
5. Consider common sizes: While not universal, many Japanese and European cars use metric sizes, with 17mm and 14mm being common. 

Tips for changing the oil plug

• Use a 6-point socket: This type of socket is more effective at gripping the bolt and prevents the head from getting rounded off. 
• Use a 3/8-inch drive socket and ratchet: This is a common size for most DIY oil changes. 
• Have a replacement plug ready: If the old drain plug is worn or stripped, you’ll need a new one to replace it. 

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.