Parts for your 2009 Subaru Impreza-Sump plug washers

2009 Subaru Impreza sump plug washers — what they do and when to replace them

Yes, the 2009 Subaru Impreza uses a sump plug washer. Subaru’s own technical literature backs this up: the Impreza 2008–2011 Service Manual (Lubrication section) specifies a replaceable drain plug gasket and a tightening torque of about 44 N·m, and the Subaru FAST electronic parts catalogue lists a crush-type “GASKET, DRAIN PLUG” (commonly supplied as genuine Subaru P/N 803916010) for EJ-series engines fitted to 2009 Impreza models. Those sources make it clear a washer is fitted and intended to be renewed during servicing.

On this Impreza, the sump plug washer is a soft-metal crush gasket (typically aluminium) that deforms once to create a reliable seal between the plug and the alloy sump. It prevents weeping and drips, helps the plug reach the correct clamping load at the specified torque, and protects the sump’s sealing face. Reusing a crushed washer can compromise all three.

For best results during servicing, a new washer should be installed at every engine oil change. That aligns with Subaru service guidance for the generation and is standard practice at dealers. Whether it’s a 2.0, 2.5, or WRX variant, the approach is the same: fit a new OEM-quality crush washer, tighten the drain plug to around 44 N·m (always verify against the specific model’s service data), and check for leaks after the refill and short run.

Handy tips for keeping the 2009 Impreza leak-free:

• Always replace the washer rather than reusing the old one, crush types are designed for single use.
• Clean the plug and sump sealing face, and start the plug by hand to avoid cross-threading.
• Torque to spec — overtightening can distort the washer or damage threads, undertightening can allow seepage.
• Don’t stack washers or add sealants, a fresh crush washer is the correct seal.
• Keep a couple of genuine washers on hand so an oil change isn’t held up.

If there’s a faint oil mist around the drain plug, a drip on the driveway after servicing, or the plug feels loose-tight-loose as it’s turned, the washer has likely been reused or over-compressed. Swapping in a new crush washer and torquing correctly almost always fixes it. Given the low cost of the part versus the grief of a leak, replacing it each service is a no-brainer for Aussie and Kiwi owners.

Popular questions

Can the sump plug washer on a 2009 Subaru Impreza be reused?
It’s a single-use crush washer, so it shouldn’t be reused. Once compressed, it can’t reliably reseal. A fresh washer at every oil change is the go.

What torque should the sump plug be tightened to?
Subaru service information for this generation cites about 44 N·m. Always confirm against the exact engine variant’s service manual and use a torque wrench.

How often should the washer be replaced?
Every engine oil change. That’s standard dealer practice and aligns with the Subaru service manual note to replace the drain plug gasket whenever the oil is changed.