What size is the oil plug nut?

There isn’t a single standard size for an oil drain plug nut. On most passenger vehicles, the hex-head size you’ll need is typically between 13 mm and 19 mm (or roughly 9/16 in to 3/4 in for SAE), with trucks and diesels often larger. The exact size depends on the make, model, engine, and even the oil pan design, so the only reliable answer is to check your owner’s manual, service data, or measure the plug on your specific vehicle. Below is a clear guide to the most common sizes and how to identify the right one safely.

Why there’s no one-size-fits-all answer

Automakers use different plug designs, materials, and torque specs. Even within the same brand, engines may differ by year or trim, and aftermarket oil pans or plugs can alter the size you’ll encounter. Adding to the confusion, “size” can refer either to the wrench size for the plug head (what socket fits) or the thread size (diameter and pitch) of the plug that screws into the pan. Knowing which one you need avoids rounded fasteners, stripped threads, or leaks.

Common wrench sizes for oil drain plug heads

These are the sizes most DIYers encounter when choosing a socket for the plug head. Use this as a starting point, then verify against your vehicle documentation or by measuring across the flats of the plug head.

• Metric hex-head (most common on modern cars): 13 mm, 14 mm, 15 mm, 17 mm, 19 mm
• Larger metric on trucks/diesels: 21 mm, 22 mm, 24 mm, 27 mm
• SAE (older domestic vehicles or aftermarket): 9/16 in, 5/8 in, 11/16 in, 3/4 in
• Internal hex/Allen (some European and motorcycle applications): 6 mm, 8 mm, 10 mm
• Torx/internal drive (select applications): T45, T50 (verify before use)

If your plug doesn’t match these, do not force a “close” socket—measure precisely or check the manual to avoid rounding the head or damaging the plug.

Common thread sizes and pitches (not the same as wrench size)

Thread specifications determine what physically screws into the pan and are essential if you’re replacing the plug. Always match the thread size and pitch exactly to prevent leaks or stripped threads.

• Passenger vehicles (typical): M12 x 1.25, M12 x 1.5, M14 x 1.5
• Larger pans/trucks: M16 x 1.5, M18 x 1.5, M20 x 1.5
• Motorcycles/small engines: M10 x 1.25, M12 x 1.25
• SAE legacy (less common today): 1/2-20, 9/16-18

Thread size and pitch are usually specified in service manuals or on replacement plug packaging; matching them is more important than matching the wrench size on the head.

How to identify your exact size

To avoid guesswork, these methods will help you confirm the correct wrench size and thread specification for your vehicle’s oil plug.

1. Check the owner’s manual or factory service information for drain plug specs.
2. Use a socket gauge or measure the plug head across the flats with calipers to find the correct wrench size.
3. If replacing the plug, remove it and measure the thread diameter and pitch with a thread gauge, or match it at a parts store by vehicle lookup.
4. Verify if your vehicle uses a crush washer or O-ring and get the correct type and size at the same time.
5. Confirm torque spec for your engine to avoid over-tightening (typically 20–35 ft-lb for many passenger cars, but always check your model).

Taking a moment to measure and verify prevents damage to the plug or oil pan and ensures a proper seal when you reinstall it.

Brand and vehicle trends (use as guidance, not gospel)

While there are exceptions, some patterns do exist across the market. Use these trends only as a preliminary guide and confirm specifics for your exact model and engine.

• Many Japanese brands (Honda, Toyota, Nissan, Mazda): often 14 mm or 17 mm hex heads; threads commonly M14 x 1.5 or M12 x 1.25
• Subaru, Hyundai/Kia: frequently 17 mm heads; threads often M16 x 1.5 or M14 x 1.5
• Domestic (Ford, GM, Stellantis): varies widely; 13–15 mm metric or 5/8 in common on older models
• German brands (VW/Audi, BMW, Mercedes): 17–19 mm hex heads or internal hex/Torx on some models; verify plastic vs metal plug types
• Trucks and diesels: 21–24–27 mm heads and larger thread sizes are common
• Motorcycles: smaller heads (12–17 mm) and some internal hex designs

Because manufacturers change designs over time, always verify by manual or measurement before selecting a tool or replacement part.

Tools and best practices

Having the right tools and techniques helps avoid mishaps during an oil change and extends the life of your oil pan threads.

• Six-point sockets to reduce the risk of rounding the plug
• Torque wrench set to the manufacturer’s spec
• New crush washer or O-ring if specified for your vehicle
• Thread gauge or calipers if replacing or verifying specs
• Brake cleaner or shop towels to clean the sealing surface

Replacing the sealing washer and tightening to spec are just as important as using the correct socket size; both steps prevent seepage and stripped threads.

Safety and fitment notes

Oil plugs are soft compared with sockets; a slightly loose fit can round off the head quickly. If a plug feels stubborn, stop and confirm the size, switch to a six-point socket, and consider gentle heat if appropriate. If threads feel gritty or cross-threaded on reinstallation, do not force it—inspect the pan threads and repair with the correct insert (e.g., time-sert) if needed.

Bottom line

Without the exact vehicle details, the best you can say is that most cars use a 13–19 mm hex head, with trucks/diesels often larger, and thread sizes commonly range from M12 to M20 with various pitches. Confirm with your manual or by measuring to avoid damage and ensure a proper seal.

Summary

There is no universal oil drain plug nut size. For most passenger vehicles, expect a 13–19 mm hex head (or 9/16–3/4 in SAE), while larger trucks and diesels may need 21–27 mm. Thread sizes frequently include M12 x 1.25/1.5, M14 x 1.5, and M16–M20 variants. Always verify your specific vehicle’s wrench size, thread size, and torque spec via the owner’s manual or precise measurement, and replace the crush washer when required.

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

There is no universal drain plug socket size; the correct size depends on the vehicle’s make and model and is typically a metric socket in sizes like 14mm, 15mm, 17mm, or 19mm. To find the exact size for your car, check your owner’s manual, inspect the bolt head, or look for a general tool set that includes a range of metric sockets. 
How to determine the correct size:

1. Check the owner’s manual: The owner’s manual for your car will often list the bolt size needed to change the oil. 
2. Inspect the bolt head: Look at the existing oil drain plug to see its size. 
3. Use a general metric socket set: Common sizes are 14mm, 15mm, 17mm, and 19mm. A set that covers these common sizes is a good start. 
4. Consider a 6-point socket: A 6-point socket is recommended over a 12-point socket because it provides a better grip and is less likely to strip a pre-tightened or damaged drain plug. 

Important considerations:

• Metric vs. SAE: Most modern cars use metric sizes, but older cars or specific components may use SAE (standard) sizes. 
• Don’t overtighten: Always avoid overtightening or forcing the drain plug, as this can lead to damage. 
• Replace the gasket: Always replace the gasket on the drain plug, as it is crucial for preventing 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 tool do I need to change an oil filter?

First you’ll need a ratchet and socket set to remove the oil drain plug, then an oil filter wrench to remove the filter. When choosing an oil filter wrench, try to find one that will match the specific filter and engages the serrations on the end of the oil filter to make the task easier.

What size nut is the oil drain plug?

The size of an oil drain plug nut is not universal and depends on the make, model, and year of your vehicle, so you must check your car’s owner’s manual or find the specific information for your car’s year, make, and model. Common sizes include metric sizes like 12mm, 14mm, 15mm, 17mm, and 21mm, with 14mm and 15mm being particularly common.
 
How to find the correct size:

1. Consult your vehicle’s owner’s manual: This is the most reliable source of information for the correct drain plug size. 
2. Look up the information online: Check for your specific vehicle’s year, make, and model on auto part websites or forums like Reddit or Stack Exchange. 
3. Visually inspect the drain plug: If possible, look at the bolt head to determine its size. 

Common metric sizes for oil drain plugs: M12 (12mm), M14 (14mm), M15 (15mm), and M17 (17mm). 
Important Tips:

• Use a 6-point socket or wrench: Opens in new tabThese provide more contact area and are less likely to strip the bolt head than 12-point tools. 
• Consider using a Vise-Grips for stubborn plugs: Opens in new tabIf a socket doesn’t fit or you’re having trouble, finely tuned Vise-Grips can be a good alternative. 
• Always replace the drain plug gasket: Opens in new tabA new gasket is crucial for preventing oil leaks and is a good idea to replace with every oil change. 

This video explains how drain plugs are categorized and why a new gasket is important: 54sunkertechYouTube · Mar 3, 2021