What Size Socket Do You Need to Remove a Drain Plug?

Most engine oil drain plugs take a 13 mm to 19 mm six-point metric socket, with 14 mm and 17 mm being the most common; some use internal hex (6 mm, 8 mm, or 10 mm) or, less often, SAE sizes like 1/2 inch or 5/8 inch. Because sizes vary by vehicle and component, confirm by checking your owner’s manual or measuring the plug head before turning a wrench.

Contents

How to Identify the Right Socket Size
Common Drain Plug Socket Sizes by Application
Tools and Materials You Will Need
Torque Specs and Best Practices
Quick Reference: Find Your Socket in Minutes
Summary

How to Identify the Right Socket Size

The fastest way to avoid rounding a plug is to identify the head type and measure it before you wrench. The following steps help you pick the correct socket every time.

Check documentation first: the owner’s manual or a service manual often lists the drain plug size and torque spec.

Inspect the plug: determine whether it is an external hex head (standard socket), an internal hex/Allen (use hex-bit socket), Torx/star, or a square plug (often accepts a 3/8 inch or 1/2 inch ratchet drive directly).

Measure across flats: use calipers or a wrench gauge on an external hex head. If it measures close to a whole millimeter, it is metric; if it measures in fractional inches, consider SAE.

Test-fit a six-point socket: start with a snug fit—14 mm and 17 mm are common for oil pans. Avoid a loose 12-point socket on tight plugs to reduce rounding risk.

Confirm thread condition: if the plug feels gritty or binds early, stop and clean the threads; never force it.

Have the right bit for internal plugs: many transmissions, transfer cases, and differentials use 8 mm or 10 mm internal hex—bring those hex-bit sockets.

Set a torque wrench for installation: note the torque now so you can re-tighten correctly after service.

Following these steps minimizes damage to the plug and pan, ensures a proper seal with the correct washer, and saves time during reassembly.

Common Drain Plug Socket Sizes by Application

While specifications vary by make and model, these are the sizes most technicians reach for first when tackling common automotive drain plugs.

Engine oil pans (cars and light trucks): 13 mm, 14 mm, 15 mm, 17 mm, 19 mm external hex; less commonly 1/2 inch or 5/8 inch SAE. Some European models use internal hex 6 mm, 8 mm, or 10 mm.

Motorcycles and small engines: typically 12 mm to 17 mm external hex; check for soft aluminum pans that require careful torque.

Manual transmissions/transfer cases/differentials: often 8 mm or 10 mm internal hex; some use 24 mm external hex; others have square plugs that accept a 3/8 inch or 1/2 inch ratchet drive.

Radiators/coolant drains: commonly plastic petcocks (no socket), but some aftermarket or heavy-duty units may have a 19 mm plastic hex—avoid over-torquing.

Crush washers/sealing rings: frequently paired with M12 or M14 drain bolts; match washer to bolt size and material (aluminum, copper, or fiber) per manufacturer guidance.

These ranges cover most scenarios, but always verify against your specific vehicle’s service information to avoid mismatches and leaks.

Tools and Materials You Will Need

A basic kit reduces the chance of rounding the plug and speeds up the job. Gather the items below before you start.

Six-point metric socket set (10 mm to 21 mm) and, if needed, SAE sockets (3/8 inch to 7/8 inch)

Ratchet (3/8 inch drive) and, for stubborn plugs, a short breaker bar

Torque wrench covering roughly 10 to 60 ft-lb (14 to 80 N·m)

Hex/Allen bit sockets (6 mm, 8 mm, 10 mm) and Torx bits if applicable

New crush washer or sealing ring matched to your drain bolt

Drain pan, shop towels, nitrile gloves, and eye protection

Penetrating oil and a wire brush for dirty or corroded plugs

Ramps or jack and stands, plus wheel chocks, for safe access

Having these on hand ensures you can remove, service, and reinstall the plug correctly and safely in one session.

Torque Specs and Best Practices

Correct torque and technique matter as much as the socket size. The points below help prevent stripped pans and future leaks.

Typical oil drain plug torque: M12 bolts often tighten around 20–25 ft-lb (27–34 N·m); M14 around 25–30 ft-lb (34–41 N·m). Always defer to the manufacturer’s spec, especially with aluminum pans.

Use a new crush washer each service unless specified reusable; install the washer in the correct orientation.

Hand-thread the plug first to avoid cross-threading; snug with a six-point socket, then torque to spec.

Warm oil drains faster: a few minutes of engine warm-up helps, but avoid working on a hot exhaust or scalding oil.

If stuck, use steady pressure with a breaker bar; avoid impacts that can crack pans. Apply penetrating oil if corroded.

For driveline fluids, always crack the fill plug first so you know you can refill before draining.

Do not use PTFE tape on bolts that seal with washers; sealants are for tapered or pipe-threaded fittings only if specified.

If threads are damaged, consider an oversized self-sealing repair plug as a temporary fix, or a proper insert/helicoil repair for a permanent solution.

Dispose of used oil and coolant at a recycling center; never pour fluids down drains or onto the ground.

Following these practices protects components, prevents leaks, and ensures a safe, clean service.

Quick Reference: Find Your Socket in Minutes

Use this rapid process if you are standing under the vehicle and need a confident answer fast.

Identify head type: external hex, internal hex, Torx, or square.

Start with a 14 mm six-point on engine oil plugs; if loose or tight, try 13 mm or 15 mm, then 17 mm as the next common step.

For internal hex on driveline plugs, test 8 mm first; try 10 mm if it is too small, 6 mm if too large.

If nothing fits snugly, measure across flats with calipers and match to the nearest socket size; avoid forcing a near-fit.

Once fitted, break free smoothly and note the size for future services.

This approach covers most vehicles quickly while minimizing the risk of rounding or damage.

Summary

The correct socket for a drain plug depends on the vehicle and component, but most engine oil plugs accept a 13 mm to 19 mm six-point socket—commonly 14 mm or 17 mm—with some using 6 mm to 10 mm internal hex. Verify by checking the manual or measuring the plug, use a snug six-point socket, replace the crush washer, and torque to spec to prevent leaks and damage.

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

You will need to check the specific make, model, and year of your vehicle because there is no universal oil drain plug wrench size. The size is typically a common metric size, like 14mm, 15mm, 17mm, or 19mm, or an equivalent fractional (SAE) size. It is best to get a socket set with a range of metric and SAE sizes to ensure you have the correct fit for your car’s drain plug.

This video demonstrates how to use a special tool to remove a rounded drain plug: 56sJimthecarguyYouTube · Nov 17, 2014
To find the correct size:

Consult your owner’s manual: to see if it specifies the drain plug size.
Inspect the bolt head: to determine if it is metric (MM) or standard (SAE).
Use a socket wrench: with the appropriate size to fit the bolt.
If you don’t have a socket wrench, you can try an adjustable wrench, but be careful, as this can strip the bolt.
Consider getting a 6-point socket: or wrench, as they provide better grip and reduce the risk of rounding the bolt head, especially if it’s old or already damaged.

Can I use a regular socket to remove an oil 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.

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.