Parts for your 1999 Subaru Forester-Sump plug washers

1999 Subaru Forester sump plug washers

Yes, the 1999 Subaru Forester uses a sump plug washer. Subaru’s Factory Service Manual for the 1999 Forester (SF series, Lubrication section) specifies a new drain plug gasket at each oil change, and the Subaru Genuine Parts Catalogue lists the aluminium crush washer as a service item for the engine oil drain plug. Common genuine part numbers are 11126AA000 (often superseded to 803916010). The manual also specifies torquing the plug to 44 N·m (about 33 ft‑lb). That makes the sump plug washer absolutely relevant to this model.

On this Forester, the sump plug washer’s job is simple but vital: it crushes slightly as the plug is tightened, sealing the joint between the plug and the sump so oil can’t seep out as the engine heats and cools. That soft aluminium ring prevents small imperfections from becoming leaks, and it saves the sump threads from the abuse of over-tightening. No need to reef on the spanner—fit a fresh washer and torque it properly and it’ll stay clean and dry.

Best practice for Aussie and Kiwi owners is to replace the washer at every oil change. Subaru’s procedure explicitly calls for a new gasket whenever the drain plug is refitted. Whether changing oil every 10,000–12,500 kilometres or on time-based intervals, treat the washer as a single-use item. Use a quality aluminium crush washer sized for Subaru’s 16 mm drain plug, start the plug by hand, then torque to 44 N·m. Avoid stacking washers or reusing a flattened one, as that invites weeping and the temptation to overtighten.

Handy tips for servicing a 1999 Forester sump plug washer:

• Clean the sump face and plug head so the new washer seats flat.
• If there’s oil mist around the plug after a service, suspect an old or incorrect washer.
• Stick with genuine or reputable aftermarket 16 mm aluminium crush washers, copper can work, but Subaru engineers specify aluminium here.

Keep a few washers in the service kit—cheap insurance against drips on the driveway and stripped threads.

What size washer does a 1999 Forester use?

It takes a 16 mm aluminium crush washer designed for Subaru oil drain plugs. Genuine Subaru part numbers frequently referenced are 11126AA000 and the later 803916010. This applies across the SF-series Forester, whether running the EJ20 or EJ25 engine. Using the correct size ensures it crushes evenly and seals first go.

Can the sump plug washer be reused?

It’s not recommended. The washer is designed to deform once to create a reliable seal. Reusing it often leads to light seepage, or it encourages overtightening to chase a seal—risking damage to the sump threads. A fresh washer is inexpensive and part of the official Subaru service procedure.

What’s the correct torque for the sump plug?

44 N·m (about 33 ft‑lb), with a new washer fitted. Always start the plug by hand to avoid cross-threading, then torque it with a calibrated wrench. If a torque wrench isn’t available, snug plus a small additional turn will usually do it—but using the proper torque is the safest bet.