Parts for your 2016 Subaru Forester-Sump plug washers

2016 Subaru Forester sump plug washers

It’s not a myth—Subaru specifies a crush-type sump plug washer for the 2016 Forester’s engine oil drain plug. The Subaru Forester (SJ, 2016, FB25/FA20) Service Manual, Lubrication (LU) section, instructs to “replace the drain plug gasket with a new one” at each oil change, and the genuine parts catalogue lists the oil drain plug gasket as an aluminium crush washer, commonly supplied as part number 803916010. Typical factory torque for the Forester’s sump plug is 44 N·m (about 33 ft‑lb). Those technical references confirm a sump plug washer is definitely used on this model.

What does the little washer actually do? On the 2016 Forester the aluminium crush washer deforms as the sump plug is tightened, filling microscopic gaps between the plug’s flange and the sump’s machined face. That controlled crush creates a reliable seal that keeps engine oil where it belongs and helps protect the alloy sump threads from over-tightening. Unlike a flat reusable washer, this single‑use crush design is engineered to compress once, so it maintains clamping force and sealing integrity through heat cycles and vibration. It’s simple, cheap, and very effective—provided it’s replaced when the oil is changed.

For servicing, the playbook is straightforward: every oil change, fit a new genuine‑spec washer, clean the mating surface, and torque the plug to spec—not “as tight as possible”. Reusing a crushed washer can lead to weeping oil, an annoying drip on the driveway, or worse, an owner chasing a non‑existent rear main seal leak. Skipping the washer entirely can push you towards over‑tightening to get a seal, risking damaged threads in the sump. For most Foresters on Australian and New Zealand schedules, that means a fresh washer every 10,000 km or 12 months with the oil and filter, whichever comes first. Keep a couple of spares on the shelf, they’re inexpensive, and having the right 16 mm Subaru washer on hand saves a parts run mid‑service. If a plug has been previously over‑tightened or the sealing face is nicked, replace the plug and then stick to the correct torque with a new washer. That habit keeps the sump healthy, the plug reusable, and the engine clean and leak‑free.

• Washer type: aluminium crush, single‑use
• Typical Subaru washer part number: 803916010 (16 mm)
• Sump plug torque: 44 N·m

Popular questions about 2016 Subaru Forester sump plug washers

Do I really need to replace the sump plug washer at every oil change?
Yes. Subaru’s service guidance calls for a new crush washer each time the plug is removed. The old washer has already deformed and won’t seal as designed if reused, which can cause small leaks or tempt over‑tightening.

What size or part number is the correct washer for this model?
The 2016 Forester typically uses Subaru’s 16 mm aluminium crush washer, widely supplied as part number 803916010. Genuine‑spec equivalents are fine, but avoid generic sizes that don’t match the plug and sump face.

What happens if the washer is left out or reused?
Expect a higher chance of seepage, and possibly a stripped sump thread if extra force is used to “make it seal”. A new washer and correct torque keep things tidy and protect the sump for the long term.