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Sump plug washers: sizes and when to replace them

3 min read · Cable ties, hoses and washers

The sump plug washer sits between the drain plug and the oil pan. Its job is to seal that joint so oil does not weep out. It is a cheap part, but the wrong one, or a tired one, can leave a drip under the car.

Should you replace it every oil change?

Crush washers are designed to deform once as the plug is tightened, which is how they seal. Because of that, many vehicle makers, workshops and parts sellers recommend a new washer at each oil change. Some people reuse washers without trouble, but a used washer may need more torque to seal, and over-tightening can damage the sump threads. Your vehicle manual is the best guide.

Finding the right size

• Inner diameter: suits the plug thread.
• Outer diameter: covers the sealing face.
• Thickness: affects how the plug sits.

Check your manual or parts book, or measure the old washer with calipers. Our sump plug washers list the inner and outer diameter and thickness for each pack, so you can match them.

Fitting tips

1. Check the old washer has come off with the plug. It can stick to the sump, and two washers will not seal.
2. Wipe the plug and the sump face clean.
3. Fit the new washer and start the plug by hand.
4. Tighten to the torque in your manual.
5. Check for drips after the engine has run.

Why buy a pack?

Workshops and home mechanics who do several oil changes a year save time by keeping the common sizes on the shelf. Our packs of 25 drop in price per pack when you buy more than one; each product page shows the price breaks.

Washer materials

• Aluminium and copper crush washers: soft metal that flattens slightly to seal.
• Fibre and composite washers: used on some plugs. Replace these at every change.
• Rubber-faced or bonded washers: a metal ring with a rubber seal.

Use the type the vehicle maker specifies for your engine.

Signs of a problem

• Oil drips from the plug after an oil change
• The plug needed more force than usual to stop a leak
• An old washer that is flattened, cracked or stuck to the sump

Tightening

Tighten the plug to the figure in your owner's or workshop manual. Over-tightening can strip the sump thread, which is a far bigger repair than a washer.

Sump plug washer sizes in our range

Our washers are listed by inside diameter (ID, which matches the plug thread), outside diameter (OD) and thickness (T). The inside diameters in our range are 7, 8, 10, 12, 14, 15, 16, 18, 20 mm. Matching the ID to the plug and the OD to the seat on the sump matters more than the brand name.

Sizes are approximate, read from the measurement marks on our product photos. Always compare with your original part.

Frequently asked questions

Can I reuse a sump plug washer?

Crush washers are designed to be used once. A new one costs little compared with an oil leak.

How do I know my washer size?

Measure the old washer's inside and outside diameters, or check your manual. Our product names list the sizes we measured.

Sizes and fitting steps in our guides are general. Check your vehicle's manual for anything specific to your car. Questions? Call 0499 001004.