Parts for your 2018 Mazda 3-Sump plug washers

2018 Mazda 3 sump plug washers — what they do and when to replace

Yes — the 2018 Mazda 3 uses a sump plug washer. Technical sources that specify this include the Mazda Workshop Manual for the BM/BN Mazda3 (Engine Oil Replacement procedure: fit the drain plug with a new washer and tighten to 30–41 N·m), and the Mazda Genuine Parts Catalogue listing a 14 mm drain plug gasket (often catalogued as 99564-1400 or 9956-41-400) for the 2018 model. Independent service guides such as Haynes for the 2014–2018 Mazda 3 also note replacing the washer at each oil change.

On a 2018 Mazda 3, the sump plug washer is a small, crush-style aluminium gasket that sits between the oil pan and the drain plug. Its job is simple but crucial: it deforms slightly when torqued, creating a reliable seal so engine oil doesn’t weep past the plug. Because it’s designed to crush once, it’s classed as a single-use consumable.

For owners keeping their Mazda 3 in top nick, replacing the sump plug washer at every oil change is cheap insurance. Reusing a flattened washer can lead to slow leaks, oily undertrays, and mess on the driveway. If there’s any sign of seeping around the plug, a fresh washer is the first thing to fit.

• Fit a new 14 mm Mazda-spec crush washer at each service (oil changes are typically every 10,000–15,000 km or 12 months in AU/NZ conditions, or as per the vehicle’s service schedule).
• Clean the mating surface on the sump and the plug head, no sealant is required with the correct washer.
• Tighten the drain plug to 30–41 N·m using a torque wrench. Over-tightening can strip threads or distort the sump, under-tightening can allow leaks.
• Hand-start the plug to avoid cross-threading, then torque to spec.
• If an aftermarket magnetic plug is fitted, a crush washer is still used unless the plug specifically includes an integrated sealing ring designed for Mazda’s sump.

Materials vary, but Mazda’s OE washer is typically aluminium. Copper aftermarket options exist, either works provided the inner diameter and thickness suit the Mazda 3 sump plug and the plug is torqued correctly.

Technical sources referenced: Mazda3 (BM/BN) Workshop Manual — Engine Oil Replacement, Mazda Genuine Parts Catalogue — Gasket, Oil Drain Plug (14 mm) for 2018 Mazda 3, Haynes service guide for Mazda 3 2014–2018 — routine maintenance notes.

Popular questions about 2018 Mazda 3 sump plug washers

What size washer does a 2018 Mazda 3 use?
The 2018 Mazda 3 uses a 14 mm crush-type sump plug washer matched to the factory drain plug. Genuine Mazda listings commonly show a 14 mm aluminium washer (often catalogued as 99564-1400/9956-41-400). Using the correct size ensures proper sealing and torque.

Can the sump plug washer be reused?
It’s not recommended. The washer is designed to crush once to form a seal. Reusing it can lead to seepage, especially after heat cycles. Always fit a new washer at each oil change for a tidy, leak-free result.

What torque should the drain plug be tightened to?
The Mazda Workshop Manual specifies 30–41 N·m for the oil drain plug on the BM/BN Mazda 3. Use a torque wrench. If one isn’t available, snug the plug firmly on a fresh washer without leaning on it, then check for leaks after warm-up.