Parts for your 2006 Toyota Prius-Sump plug washers

2006 Toyota Prius sump plug washer: fitment, purpose, and service tips

Yes, the 2006 Toyota Prius uses a sump plug washer (also called an oil drain plug gasket). Toyota’s technical sources back this up: the Toyota Electronic Parts Catalog specifies a 12 mm aluminium crush washer, part number 90430-12031, for the NHW20 Prius (2004–2009). The Toyota Repair Manual for Prius (NHW20, Engine/Hybrid System – Lubrication – Engine Oil section) directs technicians to install a new drain plug gasket and tighten the plug to approximately 27 N·m (about 20 ft·lbf) at each oil service. That combination of a crush washer and a modest torque is how Toyota achieves a clean, reliable seal without stressing the alloy sump.

On this model, the sump plug washer’s job is simple: it deforms slightly when the plug is tightened, filling microscopic gaps between the plug flange and the sump face. That controlled “crush” prevents weeping and keeps oil in, road grime out. Because aluminium work-hardens once it’s been compressed, the washer is designed as a consumable. Reusing it risks slow drips, stained driveways, and owners chasing phantom “rear main seal” leaks that are really just a tired washer.

For anyone servicing a 2006 Prius, swapping the washer is an easy win for longevity. Keep a small stash of the correct 12 mm aluminium washers (OE 90430-12031 or a quality equivalent). After draining, clean the sump face with a lint-free rag, fit a fresh washer to the plug, and snug the plug with a torque wrench to around 27 N·m. No need to swing off it—over-tightening can distort the washer, gouge the sump face, or even strip threads.

While copper or fibre washers exist, Toyota designed this application around an aluminium crush washer’s sealing characteristics. If a non-OE option is used in a pinch, make sure it’s the right size and quality, then check for any weeping after the first heat cycle.

• Replace the washer at every oil change (roughly every 10,000 km or 12 months, or as per service schedule).
• If there’s any sign of oil mist or a drip at the plug, fit a new washer and verify torque.
• Inspect the sump face for nicks, lightly dress flat if needed to help the washer seal.

Does every 2006 Prius use the same washer size?
Yes. Gen 2 Prius (NHW20) uses a 12 mm aluminium crush washer on the engine oil drain plug. Sticking with the OE style and size helps ensure a first-time seal without over-torque.

How often should the sump plug washer be replaced?
Best practice is every oil change. The aluminium crushes once, reusing it can lead to seepage. It’s a low-cost item that prevents annoying drips and callbacks.

What torque should the drain plug be tightened to?
About 27 N·m. That’s tight enough to crush the washer properly without risking thread damage. Using a torque wrench is the easiest way to get it right.