What Size Socket Do I Need for an Oil Drain Plug?

Most passenger vehicles use a socket in the 13 mm to 19 mm range (or 1/2″ to 3/4″ for SAE) for the oil drain plug, but the exact size depends on your specific engine and plug design. The only reliable way to know is to check your owner’s manual or measure the plug head directly before you start the job.

Why There’s No Single “Standard” Socket Size

Although tightening or removing an oil drain plug looks like a simple task, manufacturers use different plug sizes, materials, and thread designs. That means the socket you need can vary not just between brands, but also between models and engines within the same brand. Using the wrong socket risks stripping the bolt head, over-tightening, or failing to tighten properly—any of which can lead to slow oil leaks or, in the worst case, major engine damage.

Common Socket Sizes for Oil Drain Plugs

The most commonly used sizes fall into a fairly narrow band. Understanding these typical ranges can help you prepare the right tools before you slide under the car.

Typical Metric Socket Sizes

Most modern cars and light trucks—especially Japanese, Korean, and European models—use metric drain plugs. The head size for the plug (the part the socket grabs) usually falls within a few well-known dimensions.

The list below outlines the metric socket sizes you are most likely to encounter, along with the kinds of vehicles that often use them.

• 13 mm: Less common but seen on some small gasoline engines and compact cars.
• 14 mm: Very common on many Japanese and Korean cars (Toyota, Honda, Hyundai, Kia, Mazda, Subaru) and some smaller European engines.
• 15 mm: Found on some GM and Ford engines and occasional European models.
• 17 mm: Common on European vehicles (Volkswagen, Audi, BMW, Mercedes-Benz) and some larger four-cylinder and six-cylinder engines.
• 19 mm: Often used on larger displacement engines, some trucks, and older European or domestic vehicles.

While these sizes cover the majority of cases, not every vehicle fits neatly into this list; slight differences in design and aftermarket plugs can push you outside the “typical” range.

Typical SAE (Inch) Socket Sizes

Some older U.S. vehicles and certain domestic trucks still use SAE (inch-based) plugs. These are less common on modern cars but still important in garages and DIY setups, especially for older or classic vehicles.

The following list highlights the most frequent SAE socket sizes used for oil drain plugs and where you might see them.

• 1/2 inch: Sometimes found on smaller domestic engines or older compact cars and light trucks.
• 9/16 inch: Used on some mid-size domestic engines; can be easy to confuse with 14 mm if you’re not careful.
• 5/8 inch: Common on many older American V6 and V8 engines.
• 3/4 inch: Occasionally used on heavy-duty or older truck engines with larger drain plugs.

When working with older domestic vehicles, having this range of SAE sockets on hand can save you time and prevent damage from using an almost-but-not-quite-right size.

Special Cases: Hex, Torx, and Internal Plugs

Not every oil drain plug uses a conventional hex-head bolt. Some manufacturers opt for alternative designs that require different tools, especially on European vehicles and certain modern transmissions or differentials.

Internal Hex (Allen) Drain Plugs

Many European manufacturers, as well as some modern transmissions and differentials, use internal hex (Allen) drain plugs instead of standard external hex heads. With these, the tool inserts into the plug rather than clamping around it.

The list below summarizes the most common internal hex sizes and where they’re typically seen.

• 6 mm: Used on some smaller oil sumps, gearboxes, and differentials.
• 8 mm: Very common on European engine oil pans and transmissions.
• 10 mm: Typically found on larger sumps, heavy-duty applications, and some diesel engines.

Because internal hex plugs can strip if the wrong size is used, ensuring you have a snug, exact fit is especially important with these designs.

Torx and Specialty Plugs

While less common for engine oil, some manufacturers use Torx or other proprietary designs—more often on transmissions, transfer cases, or differentials than on the oil pan itself.

The following list covers typical specialty interfaces you may encounter on modern vehicles.

• Torx (e.g., T45, T50): Occasionally used on European or specialty models, particularly for gear oil plugs.
• Hex/Torx combination plugs: Feature both an external hex for a socket and an internal Torx or Allen for added flexibility.
• Plastic or composite plugs: Seen on some newer models (notably certain Ford, VW/Audi, and BMW engines) with large plastic heads designed for lower torque and easier replacement.

When faced with Torx or plastic plugs, it is crucial to verify the exact size and follow torque specifications strictly, as these plugs are often more fragile than traditional steel bolts.

How to Identify the Correct Socket Size for Your Vehicle

Because plug sizes vary, you should confirm the correct socket for your specific vehicle before beginning an oil change. There are several reliable ways to do this using documentation and basic measuring tools.

Check the Owner’s Manual or Service Information

Many manufacturer documents list drain plug specifications, especially in detailed service manuals and technical data sheets.

The following list details key reference sources you can use to locate the proper socket size.

1. Owner’s manual: Some manuals include oil change details and plug specs, though many only mention oil type and capacity.
2. Factory service manual (FSM): Typically includes exact plug size, torque specifications, and any special tool requirements.
3. Automaker online portals: Many brands provide digital service information that independent shops and DIYers can access, sometimes for a fee.
4. Reputable repair databases: Services like ALLDATA, Mitchell, or OEM-based apps often list drain plug specs for specific engines.

When available, factory data is the most precise source, ensuring you match the correct size and tightening torque for your specific engine and model year.

Measure the Plug Head Directly

If documentation is unclear or unavailable, you can identify the correct socket size by measuring the plug itself. This approach is especially useful when vehicles have aftermarket or replacement plugs installed.

The list below explains practical steps for measuring an oil drain plug head accurately.

1. Inspect the plug visually: Confirm if it’s an external hex, internal hex (Allen), or another specialty design.
2. Use a caliper or ruler: Measure the distance across the flats of the head (for external hex) or across the internal flats (for Allen plugs).
3. Match to your socket set: Compare your measurement with your metric and SAE sockets, checking for the closest snug fit.
4. Test fit before draining: Gently test the selected socket on the plug with the car cool and engine off to confirm a tight, non-slipping fit.

By physically measuring and test-fitting your tools, you greatly reduce the risk of rounding off the plug, which can turn a simple oil change into a far more complicated repair.

Best Practices for Removing and Reinstalling the Drain Plug

Choosing the correct socket is only part of the job; how you use it matters just as much. Proper technique protects both the plug and the oil pan threads, preventing leaks and future headaches.

Tool Choice and Technique

A quality, correctly sized socket and a stable working position are essential when breaking loose and tightening a drain plug.

The list below summarizes practical tips to safely loosen and reinstall an oil drain plug.

• Use a six-point socket: A six-point socket grips the flats of the bolt more securely than a twelve-point, reducing the chance of rounding.
• Avoid adjustable wrenches: Adjustable tools often slip and damage the plug head; sockets or box-end wrenches are safer.
• Pull steadily, not jerkily: Apply controlled pressure; sudden movements can cause the tool to slip and strip the plug.
• Consider a torque wrench on reinstallation: Tightening the plug to the manufacturer’s specified torque helps prevent both under-tightening and stripping threads.

Good tools and patient technique dramatically lower the odds of damage and make your oil change faster and more predictable.

Washer and Torque Considerations

Oil drain plugs often rely on a crush washer or gasket to seal properly. These components and the torque you apply are as critical as the socket size you use.

The list that follows outlines key points about washers and torque when servicing a drain plug.

• Replace crush washers when recommended: Aluminum or copper washers are often designed for single use and may leak if reused repeatedly.
• Know the typical torque range: Many oil drain plugs fall between about 20–35 ft-lb (27–47 N·m), but always follow the spec for your engine.
• Avoid over-tightening: Excessive torque can strip aluminum oil pans, a repair that may require heli-coils or pan replacement.
• Check for leaks after warm-up: After running the engine and bringing it to temperature, inspect the plug area for any sign of seepage.

Attention to the sealing washer and correct torque helps ensure a leak-free seal and preserves the life of the oil pan threads.

Planning Your Tools: What to Have On Hand

If you intend to change oil on different vehicles—or are unsure of your plug size—having a modest selection of tools ready will cover most situations and minimize mid-job surprises.

Recommended Socket and Tool Range

Building a small, targeted kit of sockets and related tools will equip you for the majority of common cars and light trucks.

The following list outlines a practical starter tool set for oil drain plug work.

• Metric sockets: 13 mm, 14 mm, 15 mm, 17 mm, 19 mm (six-point, 3/8″ or 1/2″ drive).
• SAE sockets: 1/2″, 9/16″, 5/8″, 3/4″ for older or domestic vehicles.
• Allen (hex) bits: 6 mm, 8 mm, 10 mm for internal hex drain plugs.
• Ratchet and/or small breaker bar: For leverage when loosening stubborn plugs.
• Torque wrench: For precise reinstallation to spec.

A compact kit like this will handle the vast majority of oil drain plugs you’re likely to encounter, from compact hatchbacks to larger sedans and many light trucks.

Summary

There is no single universal socket size for oil drain plugs, but most passenger vehicles use a metric socket between 13 mm and 19 mm, with 14 mm and 17 mm among the most common, while some older or domestic models rely on SAE sizes like 1/2″ or 5/8″. Internal hex (Allen) plugs—often 6 mm, 8 mm, or 10 mm—are also widely used, particularly on European vehicles. To avoid stripping the plug or damaging the oil pan, confirm the size via your owner’s manual or service data, or measure the plug and test-fit your socket before draining the oil. Pair the correct socket with a six-point design, the proper torque, and a fresh crush washer where required, and you’ll have a clean, leak-free oil change with minimal risk of damage.

What size wrench do I need to remove the drain plug for an oil change for a 2008 Honda CRV?

And then we want to make sure stick a drain bucket underneath. Let it drain. Out this oil doesn’t look too. Bad. It’s still get a little bit of color to it.

What size is the most common oil plug?

Most cars use oil drain plugs between 13mm and 17mm, depending on the brand.

What tool should you use to loosen the oil pan drain plug?

OTC Tools 5911A Drain Plug Pro Magnetic Remover, Black, 1/4 Inch Square Drive.

What size socket to remove oil drain plug?

3/8-inch
Place a 3/8-inch (0.9 centimeters) socket in the socket wrench, fit it over the drain plug’s nut and turn it counterclockwise. The oil drain plug should open easily, draining the used oil from the engine. Make sure to place a bucket and some newspaper under the car’s engine to catch all the draining oil.