Parts for your 2020 Subaru Impreza-Sump plug washers

2020 Subaru Impreza sump plug washers

Yes — the 2020 Subaru Impreza uses a replaceable sump plug washer (crush washer) on the engine oil drain plug. Subaru’s own documentation specifies it. The 2020MY Impreza Owner’s Manual calls for replacing the drain plug gasket at oil changes, and the Subaru Service Manual for the FB engine (Lubrication section) states “replace drain plug gasket” and gives the drain plug torque as 44 N·m (about 32.5 ft‑lb). Genuine parts catalogues list the aluminium M16 crush washer (commonly P/N 803916010) for this vehicle.

On this Impreza, the sump plug washer is a soft aluminium ring that deforms once to create a leak‑free seal between the steel drain bolt and the alloy sump. That crush action takes up tiny imperfections so the plug clamps evenly without needing to be over‑tightened. Reusing a crushed washer is a false economy — it can’t reseal properly, and the result can be annoying drips or, worse, weeping that travels down the undertray and makes it look like a rear main issue.

Best practice during servicing is simple: replace the washer at every oil change. Fit a new, clean aluminium M16 washer to the clean drain plug, snug it by hand to seat it, then torque the plug to the factory spec of 44 N·m. Don’t lean on it harder “just to be safe”, too much grunt can distort the washer, or strip sump threads — neither is a good time. If a torque wrench isn’t available, tighten to firm plus a small nip, but the proper tool is the smarter bet.

Common signs a washer needs attention include dampness around the plug after a drive, oil misting on the undertray, or a plug that seems to come loose between services. If any of that shows up, fit a fresh washer and re‑torque. Stick with OE‑style aluminium, copper and fibre can work in a pinch, but Subaru engineered this joint around an aluminium crush washer for consistent sealing and feel. Keeping a small stash of genuine or quality aftermarket M16 Subaru‑spec washers in the glovebox makes every 10,000–12,500 km service that bit easier.

Technical sources referenced: 2020MY Subaru Impreza Owner’s Manual (Maintenance/Engine Oil), Subaru Service Manual, FB Engine – Lubrication (drain plug torque and “replace gasket” instruction), Subaru Genuine Parts Catalogue listing for drain plug gasket (aluminium, M16, P/N 803916010).

• Does a 2020 Subaru Impreza have a sump plug washer?
  The 2020 Impreza uses a single‑use aluminium crush washer on the engine oil drain plug. It’s designed to be replaced at each oil change so the plug seals without over‑tightening.
• What size and part number is the washer?
  It’s an M16 aluminium crush washer. Genuine Subaru listings commonly show P/N 803916010 for this model year. Always match by VIN or engine code if unsure.
• How often should it be replaced?
  Every service when the engine oil is changed. If there’s any sign of seepage after a change, fit a fresh washer and torque the plug to 44 N·m.