Parts for your 2019 Subaru Outback-Sump plug washers

2019 Subaru Outback sump plug washers — what they do and when to replace them

Yes, the 2019 Subaru Outback uses a sump plug washer on the engine oil drain plug. Subaru’s service documentation for the 2019 Outback (Engine Lubrication section of the workshop manual) specifies fitting a new drain plug gasket whenever the plug is refitted and torqued. The Subaru genuine parts catalogue also lists an aluminium crush-type drain plug gasket for this model (commonly referenced as 16 mm ID, Subaru part number 803916010). This confirms the sump plug washer is a required service item, not an optional extra.

A sump plug washer on the 2019 Outback is a small but critical bit of kit. It’s an aluminium “crush” gasket that deforms slightly when the drain plug is tightened, creating a reliable seal between the plug and the alloy sump. That controlled crush stops weeping and protects the sump threads from over-tightening as the washer absorbs the load. On Aussie and Kiwi roads where cars see plenty of heat cycles and long runs, a fresh washer at each oil change is cheap insurance against leaks on the driveway.

For this model, the washer is designed as a single-use item. Reusing it can leave a groove that won’t seal as well the second time, and that’s how slow drips start. Best practice is to fit a new 16 mm aluminium crush washer at every service when the oil is drained. Tighten the drain plug to the Subaru workshop spec of about 42 N·m (31 ft‑lb). That torque allows the washer to deform properly without risking damage to the sump. If the plug has ever been over-tightened, it’s worth a quick inspection of the threads, fix any damage before refilling with oil.

Genuine Subaru washers or quality equivalents that match the size and material are both fine. As a note for completeness, the CVT transmission on some Outback variants also uses a drain plug gasket, but it’s a different spec — don’t mix them up. After the oil change, always wipe the area clean, run the engine, and check for any sign of seepage. A dry sump after a short road test means the washer has done its job.

• Replace the sump plug washer at every oil change — don’t reuse.
• Use a 16 mm aluminium crush washer (e.g., Subaru 803916010 or equivalent).
• Torque the drain plug to about 42 N·m (31 ft‑lb) and check for leaks.

Technical references: Subaru 2019 Outback workshop manual (Engine Lubrication: drain plug installation requires a new gasket and specified torque), Subaru genuine parts catalogue listing for Oil Drain Plug Gasket (aluminium crush type, 16 mm ID, part no. 803916010).

Popular questions

What size sump plug washer does a 2019 Subaru Outback use?
The 2019 Outback uses a 16 mm inner-diameter aluminium crush washer on the engine oil drain plug. The common Subaru part reference is 803916010. Using the correct size and material ensures the washer crushes properly and seals first go.

How often should the sump plug washer be replaced on a 2019 Outback?
Every time the sump plug is removed — typically at each engine oil change. They’re designed for single use, so replacing them prevents weeping and avoids over-tightening the plug to chase a seal.

What torque should the engine oil drain plug be tightened to?
About 42 N·m (31 ft‑lb) for the 2019 Outback’s engine sump plug. That torque allows the aluminium washer to deform and seal correctly. If unsure, confirm against the workshop manual for your exact engine variant.