Parts for your 2012 Lexus Is-Sump plug washers

2012 Lexus IS Sump Plug Washers

Based on Lexus/Toyota technical documentation, a sump plug washer (also called an oil drain plug gasket) is indeed fitted and required on the 2012 Lexus IS. The Lexus IS 250/350 Repair Manual (TIS) procedure for engine oil replacement specifies “install a new gasket to the drain plug” and then tighten to the specified torque (about 39 N·m/29 ft·lbf). The Toyota/Lexus Genuine Parts catalogue lists the drain plug gasket as part number 90430-12031 (12 mm aluminium crush type) for IS250/IS350 of this era. The owner’s manual oil change guidance also calls for fitting a new drain plug gasket at refit. So yes—this model uses a sump plug washer by design.

On the 2012 Lexus IS, the sump plug washer is a small, single-use aluminium crush gasket that seals the drain plug to the sump. When the plug is torqued, the washer deforms slightly to fill any microscopic gaps, keeping engine oil where it belongs and helping avoid seepage or drips on the driveway. Because it crushes to make that seal, it’s not meant to be reused.

As part of regular servicing, it’s best practice to replace the washer at every oil change—typically every 10,000–15,000 kilometres or 6–12 months, depending on your service schedule and driving. Fresh engine oil and filter do the heavy lifting, but this little washer is the finishing touch that makes the job tidy and leak-free.

• Use the correct size: M12 aluminium crush washer (Toyota/Lexus 90430-12031 or quality equivalent).
• Clean the sump sealing face and the plug before refitting.
• Torque the drain plug to approx. 39 N·m (29 ft·lbf) unless your specific engine spec states otherwise—don’t overtighten.
• After the first drive, have a quick look under the car to confirm there’s no weeping around the plug.

Reusing a flattened or nicked washer can lead to slow leaks, messy undertrays, and the headache of redoing the job. Signs the washer’s had it include oil misting around the plug, a faint oil drip, or a washer that’s visibly grooved or hard. Given how inexpensive the part is, swapping it with each service is the smart play for long-term reliability.

For owners who like OEM precision, stick with the genuine part number above. Quality aftermarket M12 aluminium crush washers are fine too—just avoid fibre or rubber substitutes on this application, as the factory design expects a metal crush seal.

Popular questions about 2012 Lexus IS sump plug washers

What size sump plug washer does a 2012 Lexus IS use?
The 2012 Lexus IS uses an M12 aluminium crush washer. The common genuine part number is 90430-12031. Most reputable aftermarket brands label it as a 12 mm Toyota/Lexus drain plug gasket. If buying a multipack, ensure it’s for an M12 plug and designed as a crush washer, not a reusable flat shim.

How often should the sump plug washer be replaced?
Replace it at every oil change. It’s a single-use crush washer, so once compressed it won’t seal as reliably a second time. Given the low cost and the risk of drips if reused, it’s simply good maintenance to fit a new one each service.

What’s the correct torque for the drain plug when using a new washer?
About 39 N·m (29 ft·lbf) is the typical spec cited in Lexus service documentation for the IS250/IS350 engines of this model year. Always confirm for your exact engine code, but avoid overtightening—let the crush washer do its sealing work.