Parts for your 2020 Mazda 3-Sump plug washers

2020 Mazda 3 sump plug washers

Based on technical sources, the 2020 Mazda 3 (BP series) uses a replaceable crush-type sump plug washer on the engine oil drain plug. The Mazda 3 (BP) Workshop Manual available via Mazda’s service information (MGSS) directs technicians to “replace the gasket of the drain plug with a new one” during engine oil replacement, and the Mazda genuine parts catalogue for BP-series engines lists a “GASKET, DRAIN PLUG” for the sump. Local fitment guides from major aftermarket suppliers in Australia and New Zealand also specify an M14 crush washer for 2019-on Mazda 3 models. So yes—this vehicle is designed to run a sump plug washer.

For the 2020 Mazda 3, the sump plug washer is a small but crucial bit of kit. It’s a soft alloy “crush” ring that sits between the drain plug head and the sump. When the plug is tightened, the washer deforms slightly to create a reliable seal. That crush action fills tiny imperfections in the mating surfaces, helping stop annoying drips, slow weeps, and dust-attracting oil mist around the plug area. It also protects the sump face from damage by spreading the load as the plug is tightened.

Because it’s designed to deform once, it’s a single-use item. Re-using a flattened washer often leads to micro-leaks, over-tightening to chase a seal, or chewed-up threads. Best practice for a 2020 Mazda 3 is to replace the sump plug washer at every oil change—simple, cheap insurance for a tight, clean seal. Genuine and quality aftermarket options in aluminium or copper both do the job, the key is using the correct size (most BP-series Mazda 3 models use an M14 washer—owners should confirm against their engine variant or VIN when ordering).

Good servicing habits make a difference:

• Always fit a new washer at each oil and filter change.
• Clean the sump face and plug head so the new washer sits flat.
• Avoid overtightening—use a torque wrench to the spec in the Mazda workshop manual.
• Inspect the plug, replace it if the hex is rounded or the threads are tired.
• Keep a couple of spare washers in the glovebox or tool kit for future services.

Tell-tale signs a washer needs attention include a small oil spot on the driveway after a service, a faint oil film around the drain plug, or a plug that seems to “bottom out” too easily when tightening. Swapping in a fresh crush washer almost always sorts it.

FAQs

Does a 2020 Mazda 3 need a new sump plug washer every oil change?
Yes. The washer is a single-use crush type. Replacing it at each oil change helps ensure a proper seal without over-tightening, keeping the sump face and threads in good nick.

What size sump plug washer fits a 2020 Mazda 3?
Most BP-series Mazda 3 models use an M14 crush washer. Variations can exist by engine code, so it’s smart to confirm with the VIN or check the workshop manual/parts listing when buying.

Can the old washer be re-used if it isn’t leaking?
It’s not recommended. A previously crushed washer can seal poorly under heat cycles and vibration, leading to weeps later on. A fresh washer is inexpensive and far more reliable.