Vehicle Fitment – GReddy MD-03
The GReddy MD-03 is intended for Subaru vehicles using an M20×1.5 engine oil drain plug.
Common application candidates include:
| Years | Make | Model | Engine |
|---|---|---|---|
| 2002–2014 | Subaru | Impreza WRX / WRX | EJ-series turbocharged flat-four |
| 2004–2021 | Subaru | Impreza WRX STI / WRX STI | EJ257 turbocharged flat-four |
| 2000–2012 | Subaru | Outback | Selected EJ/EZ engines |
| 2000–2010 | Subaru | Legacy | Selected EJ/EZ engines |
| 1998–2010 | Subaru | Forester | Selected EJ-series engines |
| 1998–2011 | Subaru | Impreza | Selected EJ-series engines |
| 2003–2006 | Subaru | Baja | Selected EJ-series engines |
Fitment warning: These are application candidates based on Subaru engine families and aftermarket listings, not manufacturer-confirmed fitment for every trim. Subaru changed drain plug configurations on some models, particularly around the 2010–2011 period. Confirm the original drain plug’s thread size before ordering.
The MD-03 is not intended for Subaru FA engines using the M16×1.5 drain plug, including the first-generation BRZ and 2015–2021 FA20-powered WRX.
How a Magnetic Oil Drain Plug Works
A conventional oil drain plug seals the bottom of the engine oil pan.
The GReddy MD-03 performs the same basic function while adding a neodymium magnet at its inner tip.
As oil moves through the engine and returns to the oil pan, iron-based particles can come into contact with the magnet and remain attached to it.
This helps collect certain types of metallic wear debris.
A magnetic drain plug is particularly useful for inspecting debris during an oil change because collected material can be examined after the plug is removed.
However, a magnet does not attract aluminum, copper, or other non-ferrous contaminants, and it does not replace the engine’s oil filter.
Why Subaru EJ Engines Benefit From Proper Oil Maintenance
Subaru EJ-series engines use a horizontally opposed cylinder arrangement and depend on consistent lubrication to protect crankshaft bearings, camshafts, pistons, and other moving components.
Turbocharged WRX and STI applications place additional thermal and mechanical demands on the lubrication system.
Maintaining the correct engine oil level, viscosity, and service interval remains essential.
A GReddy magnetic oil drain plug adds a supplemental method of collecting ferrous debris, but it cannot compensate for inadequate oil pressure, poor maintenance, or internal engine damage.
If your engine has a history of sludge or neglected oil changes, our Engine Oil Sludge Causes and How to Fix It guide explains the importance of diagnosing oil contamination before it causes more serious problems.
5,000-Gauss Neodymium Magnetic Tip
GReddy advertises a magnetic strength of approximately 5,000 gauss for its Magdrain plug.
Neodymium magnets are commonly used in compact applications where a strong magnetic field is desirable.
Inside an engine oil pan, the magnet can attract iron-based wear particles that come sufficiently close to its tip.
Fine metallic residue on a magnetic drain plug may occur during engine operation, but unusual amounts of debris, sharp fragments, or large metallic pieces deserve further investigation.
The plug should be cleaned and inspected during every oil change.
GReddy MD-03 vs. MD-04: Choosing the Right Subaru Drain Plug
Not every Subaru uses the same oil drain plug.
| Model | Part number | Thread | General application |
|---|---|---|---|
| GReddy MD-03 | 13901303 / 23901303 | M20×1.5 | Most compatible non-FA Subaru engines |
| GReddy MD-04 | 13901304 / 23901304 | M16×1.5 | Subaru FA-series applications, including BRZ and FA20 WRX |
These parts are not interchangeable.
An M20×1.5 drain plug cannot be installed in an M16×1.5 oil pan without damaging the threads.
Always verify the oil pan’s original thread size before purchasing.
Installation Instructions
Installing the GReddy MD-03 can be performed during a routine engine oil change.
- Park the vehicle on a level surface and allow the engine to cool sufficiently for safe servicing.
- Raise and support the vehicle correctly if additional access is needed.
- Position a suitable drain pan underneath the engine.
- Remove the existing oil drain plug and drain the engine oil.
- Inspect the oil pan’s threads and sealing surface.
- Verify that the GReddy MD-03 matches the original plug’s thread diameter and pitch.
- Install a suitable new M20 sealing washer.
- Thread the GReddy drain plug into the oil pan by hand.
- Tighten using the applicable GReddy installation instructions and confirmed torque specification for the plug and oil pan.
- Complete the oil and filter change, start the engine, and inspect for leaks.
Important: Do not automatically use the factory steel drain bolt’s torque specification on an aftermarket aluminum drain plug. Confirm the appropriate torque for the installed GReddy component.
Cleaning the Magnetic Tip During Oil Changes
When the drain plug is removed, inspect the magnetic tip for accumulated debris.
Use a clean lint-free cloth to remove collected particles.
Look for unusual metallic fragments or excessive buildup.
Check the plug’s threads, magnetic tip, and sealing surface before reinstalling it.
Replace the sealing washer as required to help prevent oil leaks.
GReddy offers the matching M20 replacement washer set under part number 13901393 / 23901393.
Frequently Asked Questions
What Subaru models fit the GReddy 13901303?
It is intended for Subaru engines using an M20×1.5 drain plug, including many EJ-powered WRX, STI, Impreza, Forester, Legacy, and Outback applications.
Does it fit a 2002–2014 Subaru WRX?
Aftermarket fitment catalogs list the 2002–2014 EJ-powered WRX. Verify the drain plug size if the oil pan has been replaced or modified.
Does it fit a Subaru WRX STI?
The MD-03 is commonly listed for EJ257-powered WRX STI applications. Confirm the oil pan drain thread before installation.
Does it fit a 2000–2012 Subaru Outback?
It may fit selected Outback engines in that range, but the entire 2000–2012 range should not be treated as guaranteed fitment because engine and drain plug configurations vary.
Does it fit a 2015 Subaru WRX?
No, not for the standard FA20-powered WRX oil pan. That application uses the M16×1.5 MD-04.
Does it fit a Subaru BRZ?
No. The first-generation FA20 BRZ uses the MD-04 M16×1.5 application.
Does the magnet attract all metal particles?
No. It attracts ferrous metals such as iron and steel, but not aluminum or copper.
Does it replace an oil filter?
No. The magnetic drain plug supplements conventional oil filtration.
Will it extend my oil-change interval?
No guaranteed oil-change interval extension has been established. Follow the vehicle manufacturer’s recommended maintenance schedule.
Is the drain plug reusable?
Yes, provided it remains undamaged and is installed with an appropriate sealing washer.
Upgrade Your Subaru Oil Maintenance With GReddy
The GReddy 13901303 MD-03 Magnetic Oil Drain Plug offers a straightforward way to add magnetic ferrous-particle collection to compatible Subaru engine oil pans.
With its 5,000-gauss neodymium magnet, hard-anodized aluminum construction, and M20×1.5 thread, it is a practical maintenance upgrade for properly matched Subaru applications.
Whether you’re maintaining an EJ-powered WRX, servicing a Subaru STI, or keeping an older Outback on the road, the GReddy MD-03 makes it easier to inspect collected magnetic debris during regular oil changes.
Choose the GReddy MD-03 for Subaru oil pans requiring an M20×1.5 drain plug. Verify thread compatibility before installation.
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