GReddy Magnetic Oil Drain Plug - FRS/BRZ/86

Greddy Magnetic Oil Drain Plugs in general, are a simple way to help remove harmful metallic elements floating within your oil. This will improve overall lubricating qualities of the oil, and it will help prolong the life of your engine.

Here are the details:

Note: 

Due to a different oil pan design, some Subaru OEM oil pans have an internal screen on the inside of the pan where the drain plug sits. If the screen touches the tip of the drain plug, it will be too long and will not be able to sit flush in the pan. There is no way to tell if your car has this screen aside from using a flashlight and checking the drain plug hole during an oil change.

A couple of years ago (Late 2010) Subaru began using a new size engine drain plug on some models from an M20 to the smaller M16X1.5. If the wrench required to take off the plug is 14mm then your car needs the M16 plug.