Parts for your 2017 Subaru Forester-Sump plug washers

2017 Subaru Forester sump plug washers — what they do and when to replace them

Yes, the 2017 Subaru Forester uses a sump plug washer (also called an oil drain plug gasket). Subaru’s service literature and parts catalogues for the 2017MY Forester (FB25, FA20, and EE20 variants) specify an aluminium crush-type washer that’s replaced whenever the drain plug is removed. Genuine parts listings commonly show the aluminium 16 mm drain plug gasket (Subaru P/N 803916010) for this model year, and workshop procedures call for fitting a new gasket at each engine oil change.

A sump plug washer is a simple, soft-metal ring that sits under the drain plug and creates a reliable seal between the plug and the oil pan. On the Forester, the aluminium crush washer deforms slightly as the plug is tightened, filling microscopic gaps so engine oil can’t weep past. That one-time “crush” action is what keeps things leak-free through heat cycles and vibrations, which is especially important on Subarus that see daily commuting, long road trips, or gravel back roads across Australia and New Zealand.

As part of routine servicing on a 2017 Subaru Forester, replacing the sump plug washer is a small but important step. It helps prevent annoying drips on the driveway, keeps oil level consistent between services, and avoids over-tightening the plug to chase a seal. The washer is inexpensive and designed to be single-use, reusing it risks seepage or, worse, having to crank the plug harder and stressing the threads in the pan.

Good workshop practice for this model includes:

• Always fit a new, correct-size aluminium crush washer at every oil change.
• Wipe the sealing face on the pan and the plug head spotless before refitting.
• Tighten the plug to the specified torque from Subaru service information—no “gorilla grip”.
• If the old washer is stuck to the pan, remove it carefully, never double-stack washers.
• Keep a couple of spare genuine or OE-equivalent washers in the service kit.

The right washer makes the job tidy, quick, and repeatable. For anyone maintaining a 2017 Forester at home or in a workshop, swapping the sump plug washer every service is cheap insurance for a clean, leak-free result.

Technical sources referenced

• Subaru Forester 2017MY service information (Engine lubrication section): specifies replacing the drain plug gasket when changing engine oil.
• Subaru Genuine Parts catalogue (2017 Forester FB/FA/EE engines): oil drain plug gasket, aluminium crush type, commonly listed as 16 mm (e.g., P/N 803916010).
• Subaru Warranty and Maintenance guidance (AU/NZ): scheduled engine oil service procedures note use of a new drain plug gasket.

FAQs

Do you really need to replace the sump plug washer every service?
Yes. The aluminium washer is designed to crush once to form a perfect seal. Reusing it can lead to weeping, and cranking the plug tighter to compensate can risk damaging threads. Given the tiny cost, it’s a smart replace-every-time item.

What size sump plug washer does a 2017 Subaru Forester use?
Most 2017 Forester variants take an aluminium 16 mm crush washer. Because trims and engines vary, it’s best to match by VIN or engine code when ordering, or use the genuine Subaru-listed gasket for that model year.

Can a copper washer be used instead of aluminium?
A correctly sized copper crush washer can work in a pinch, but Subaru specifies aluminium for this application. For best fit and consistent torque/seal behaviour, use the genuine aluminium gasket or an OE-quality equivalent.