Parts for your 2013 Lexus Is-Sump plug washers

2013 Lexus IS sump plug washers — what they do and when to replace them

Based on Lexus/Toyota technical references, a sump plug washer is fitted to the 2013 Lexus IS range (IS 250/350, XE20 series). The Lexus/Toyota Electronic Parts Catalogue lists an engine oil drain plug gasket for these models (Toyota/Lexus part number 90430-12031, aluminium crush type), and the factory Repair Manual specifies refitting with a new gasket and tightening the drain plug to approximately 39 N·m. That confirms the sump plug washer is relevant and required on this vehicle.

On the 2013 Lexus IS, the sump plug washer is a simple but crucial bit of kit. It’s a soft aluminium crush gasket that sits under the drain (sump) plug on the engine’s oil pan. When the plug is torqued to spec, the washer deforms to create a leak-tight seal between the plug and the pan. That crush action is why it’s considered single-use — once compressed, it won’t spring back reliably for the next service.

For owners and workshops across Australia and New Zealand, the easy rule is: replace the sump plug washer at every oil change. It’s cheap insurance against oil weeps and the mess, risk, and cost that come with them. Lexus/Toyota specifies an aluminium gasket (commonly 90430-12031) to match the M12 drain plug used on the IS 250/350 of this era. Sticking to OEM-spec material and size helps protect the alloy sump threads and ensures the crush seal forms correctly at the factory torque (about 39 N·m). Over-tightening to compensate for a tired washer is a quick way to damage threads — better to fit a new washer and torque it right.

What to look for? If there’s a light film of oil around the plug after servicing, or a drip forming under the belly pan, the washer’s a prime suspect. When servicing, always clean the sealing faces, confirm the old gasket has been removed (they can stick), fit a new washer, and torque the plug with a calibrated wrench. Avoid reusing copper or generic washers that don’t match the Lexus spec — they can seal poorly or require higher torque.

• Replace the sump plug washer every oil change.
• Use OEM-spec aluminium gasket (e.g., 90430-12031).
• Tighten the drain plug to ~39 N·m on refit.

What size and type of sump plug washer does a 2013 Lexus IS use?

The 2013 IS 250/350 typically uses an M12 aluminium crush washer (Toyota/Lexus p/n 90430-12031). It’s designed to deform once and provide a dependable seal at the specified torque. Sticking with the OEM-spec aluminium type helps prevent over-tightening and protects the sump threads.

How often should the sump plug washer be replaced on a 2013 Lexus IS?

Replace it at every oil change. The washer is single-use, reusing it risks a weep or drip. Given the low cost versus the hassle of an oil leak, swapping it each service is the sensible move.

Can a copper washer be used instead of aluminium on this model?

While a quality copper washer can seal, Lexus/Toyota specifies an aluminium crush washer for the IS of this era. Aluminium compresses predictably at the factory torque and is kinder to the alloy sump. If copper is used, confirm correct thickness and sealing, but the OEM aluminium gasket remains the preferred choice.