Parts for your 2016 Subaru Legacy-Sump plug washers

2016 Subaru Legacy sump plug washer — what it does and when to replace it

Technical sources confirm the 2016 Subaru Legacy is fitted with a sump plug washer (also called an oil drain plug gasket). The Subaru Factory Service Manual for 2015–2017 Legacy/Outback models specifies replacing the aluminium drain plug gasket at each oil change, and the Subaru Genuine Parts Catalogue lists the correct part as an aluminium crush washer (Subaru P/N 803916010, 16 mm). For torque, the service manual specifies 42 N·m (31 lb·ft) for the 2.5‑litre FB25 and about 44 N·m (33 lb·ft) for the 3.6‑litre EZ36.

On this Legacy, the sump plug washer’s job is simple but critical: it crushes slightly as the plug is tightened, forming a gas‑tight, oil‑tight seal between the plug and the sump. That single‑use deformation fills minute imperfections so oil doesn’t creep past and leave drips on the driveway. Reusing a crushed washer can lead to weeping, over‑tightening, or a damaged sump thread — none of which anyone wants.

Best practice per Subaru’s service guidance is to fit a new washer at every oil change. Pop the old washer off the plug, wipe the sealing face on the sump, slip on a fresh 16 mm aluminium washer, then torque the plug to spec — 42 N·m for the 2.5 and around 44 N·m for the 3.6, checking the exact figure in the vehicle’s service data. Hand‑start the plug to avoid cross‑threading, don’t stack washers, and avoid “gorilla tight” — the crush washer does the sealing, not brute force.

Owners in Australia and New Zealand will find genuine‑spec aluminium washers seal more consistently than copper or fibre alternatives on these engines. If a different brand is used, match the dimensions and style to the OEM part. After refilling, run the engine for a minute, shut it down, and inspect the plug area with a torch. A clean, dry plug face after a short drive is the sign of a good seal.

• Replace the washer every service interval (each oil change).
• Use an OEM‑equivalent 16 mm aluminium crush washer (P/N 803916010).
• Tighten to the correct torque, recheck for leaks after the first run.

FAQs

Does the 2016 Subaru Legacy need a new sump plug washer at every oil change?
Yes. Subaru’s factory guidance calls for replacing the aluminium crush washer every time the plug is removed. It’s a single‑use seal designed to deform once for a reliable, drip‑free seal.

What size sump plug washer does the 2016 Legacy use?
The 2016 Legacy uses a 16 mm aluminium crush washer. The genuine Subaru part number commonly referenced is 803916010, matching the sump plug and sealing face used on FB and EZ engines of this model year.

What torque should the sump plug be tightened to?
For the 2.5‑litre FB25, the service manual specifies about 42 N·m (31 lb·ft). For the 3.6‑litre EZ36, it’s about 44 N·m (33 lb·ft). Always confirm against the exact engine and manual for the vehicle.