Parts for your 2023 Subaru Impreza-Sump plug washers

2023 Subaru Impreza sump plug washers — what they do and when to replace

Technical sources confirm the 2023 Subaru Impreza does use a sump plug washer. The Subaru Service Manual for the 2023MY Impreza (FB20 engine, Lubrication) and the Subaru Genuine Parts Catalogue specify a single‑use aluminium crush washer (often called a drain plug gasket) for the engine oil drain plug. The genuine part commonly referenced is 803916010 (16 mm), and the plug is tightened to the factory torque of about 30 N·m. Those documents also note the washer should be replaced at each oil change.

For owners and workshops alike, this little ring does a big job. The sump plug washer deforms slightly as the plug is torqued up, creating a reliable seal between the plug and the alloy sump. That controlled “crush” keeps engine oil where it belongs, helps maintain correct torque on the plug, and avoids the temptation to overtighten. On the 2023 Impreza, it’s considered a routine service consumable, just like the oil filter.

Best practice is simple: swap the washer every service, whether the Impreza is on a logbook interval or getting an extra oil change for peace of mind. Reusing a flattened or nicked washer can lead to weeping oil, drips on the driveway, or—worse—over‑tightening the plug to chase a seal. Stick with the correct 16 mm aluminium crush washer to suit the M16 drain plug. Quality aftermarket is fine, but genuine spec keeps things tidy and consistent.

A few quick tips the team always follows under the bonnet:

• Always replace the washer when the oil and filter are changed.
• Clean the mating faces on the sump and plug, no sealant or tape is needed.
• Tighten the plug to around 30 N·m using a torque wrench—no “gorilla tight”.
• After a short drive, check for any fresh film of oil around the plug.

Signs the washer’s due (or has been reused) include a faint oil halo around the drain plug, a drip after parking overnight, or a washer that’s visibly gouged or dead flat. Keeping a few spare Subaru-spec washers on the shelf makes servicing smoother, keeps the FB20 tidy and leak‑free, and protects the alloy sump threads from unnecessary strain.

Referencing Subaru’s service literature and parts data is the reason this advice is so consistent: they call for a fresh aluminium crush washer at every oil change on the 2023 Impreza, no ifs or buts.

Popular questions about 2023 Subaru Impreza sump plug washers

Does the 2023 Subaru Impreza actually have a sump plug washer?
Yes. Subaru’s service manual and parts catalogue specify a single‑use aluminium crush washer for the FB20 engine’s drain plug. It’s designed to be replaced every oil change and the plug tightened to about 30 N·m to seal properly without over‑stressing the sump.

Can a copper washer be used instead of aluminium?
Aluminium is what Subaru specifies, and that’s the safest bet. A correctly sized copper washer can seal, but it changes the crush characteristics and torque feel. If copper is used in a pinch, make sure it’s the right size for the M16 plug and be meticulous with torque—then swap back to the OEM‑style aluminium washer at the next service.

How often should the sump plug washer be replaced?
Every oil change. It’s a low‑cost part that prevents leaks and saves the sump threads by avoiding overtightening. Whether the Impreza is serviced by the book or more frequently, plan on a fresh washer each time the oil drains.