What Size MM Socket Fits Your Oil Drain Plug?

There is no single millimeter socket size for every oil drain plug; sizes such as 13 mm, 14 mm, 15 mm, and 17 mm are examples you may encounter, but the correct size depends on your vehicle and the plug installed. Your best starting point is your vehicle’s service information, which can identify the drain plug size and the tightening specification for your engine.

If you do not have that information, try metric sockets on the plug with the engine off and the vehicle safely supported, choosing the one that fits fully over the head without noticeable play. Do not force a socket onto the plug or use one that rocks on the head, because either approach can damage the plug and make removal more difficult.

A six-point socket is a practical choice for a six-sided drain plug because it contacts the flat sides of the head, while a wrench may be useful when there is not enough clearance for a socket and ratchet. Whichever tool you use, seat it completely on the plug and apply steady pressure rather than jerking the handle.

Some drain plugs use an internal hex or another drive type instead of an external six-sided head, so a standard socket may not be the right tool at all. If the plug looks worn, modified, or different from what your service information describes, identify its drive and size before attempting to loosen it.

Park on a level surface, secure the vehicle, and use properly rated supports if you need to raise it; never work beneath a vehicle supported only by a jack. Place a drain pan under the plug, and take care around hot oil and nearby components before loosening it.

When reinstalling the plug, follow the vehicle manufacturer’s instructions for the sealing washer and tightening torque, since overtightening can damage the plug or oil pan threads. Start the plug by hand to help avoid cross-threading, then use the specified tool and torque setting before checking for leaks after the oil change.

The drain plug and oil filter are separate parts, and the tool that fits one should not be assumed to fit the other. Our 14-Piece Low-Profile Oil Filter Socket & Wrench Cap Set is an oil filter tool set, so you should select your drain plug socket independently based on the plug itself.

For more on the featured set, visit our oil filter cap set fit guide. Keeping the correct drain plug tool and filter tool ready before you begin can help you avoid interrupting the job to find a different size.