Parts for your 2005 Subaru Forester-Sump plug washers

2005 Subaru Forester sump plug washers

Technical sources confirm the 2005 Subaru Forester uses a replaceable sump plug washer. The Subaru Factory Service Manual for MY2005 Forester (EJ25, Lubrication section) specifies replacing the drain plug gasket at each oil change, and the Subaru Genuine Parts catalogue lists a 16 mm aluminium crush washer for the engine oil drain plug (commonly referenced as gasket p/n 11126AA000 for EJ25 engines, which includes 2005 Forester models).

On a 2005 Forester, the sump plug washer does the quiet but crucial job of sealing the engine sump when the oil is changed. It’s a soft, single-use aluminium crush washer that deforms slightly as the plug is torqued up, creating a proper seal between the plug head and the sump face. That crush action prevents weeps and drips, protects the mating surfaces from galling, and helps the plug reach the correct clamping load at the specified torque.

Best practice is to fit a new washer at every service. Subaru documentation calls for replacement each time the plug is removed, and that’s the smart play for Aussie and Kiwi workshops: the part is inexpensive and it saves chasing nuisance leaks later. For the Forester’s EJ25 engine, torque the drain plug to about 44 N·m (use a torque wrench, not “tight enough by feel”). Over-tightening risks damaging threads, under-tightening can allow a slow seep.

Material and size matter. The Forester takes a 16 mm aluminium crush washer. Copper and reusable types exist, but the OE-style aluminium washer is designed to compress predictably at the specified torque and is the safest bet for a tidy seal. If a reusable sealing washer is trialled, it should be inspected carefully and torqued accurately, but most technicians will still opt for a fresh aluminium washer at each oil change.

Quick checks after a service should include a wipe-down around the plug, a few minutes of engine running, and then a look for any tell-tale film or drip. If there’s oil mist around the plug, odds are the washer was missed, reused when it shouldn’t have been, or the torque wasn’t dialled in. Keeping a small pack of the correct 16 mm Subaru washers on the shelf makes life easier when the next 10,000 km or six-month service rolls around.

• Use a new 16 mm aluminium crush washer each oil change
• Tighten the drain plug to ~44 N·m
• Clean the mating faces, never use sealants or thread tape

Popular questions about 2005 Subaru Forester sump plug washers

What size washer does the 2005 Forester use?
Both the 2.5-litre non‑turbo and turbo variants use a 16 mm aluminium crush washer on the engine oil drain plug. This matches the specification shown in Subaru’s parts listings for EJ25 engines used in 2005 Foresters.

How often should the sump plug washer be replaced?
Every oil change. The factory service guidance is to replace the gasket whenever the plug is removed. It’s a low-cost item that helps guarantee a clean seal and correct torque, so workshops and DIYers in AU/NZ typically change it at each 10,000 km (or six-month) service interval.

Can a copper or reusable washer be used instead?
It can work if the size is correct and torque is spot-on, but the OE-style 16 mm aluminium crush washer is preferred. It compresses exactly as intended at ~44 N·m, reducing the risk of seepage. If a reusable type is tried, inspect it closely and replace at the first sign of marking or distortion.