Parts for your 2015 Mitsubishi Lancer-Sump plug washers

2015 Mitsubishi Lancer sump plug washers — what they do and when to replace them

Yes, the 2015 Mitsubishi Lancer uses a sump plug washer. Technical references including the Mitsubishi Lancer Workshop Manual (Engine Lubrication section, 4B11/4B12 engines), the Mitsubishi ASA electronic parts catalogue (listing a replaceable oil drain plug gasket for these engines), and the Haynes Mitsubishi Lancer 2007–2017 repair manual all specify a sealing washer/crush washer on the engine oil drain plug. It’s a normal, service-replaceable part on petrol Lancers of this era.

On a 2015 Lancer, the sump plug washer is a small, single-use seal that sits under the drain plug head to keep engine oil inside the sump. Most are aluminium or copper “crush” washers that deform once to match the mating surfaces. That crush action creates a reliable seal without needing to over-tighten the plug, helping prevent leaks and avoiding damage to the alloy sump.

As part of routine servicing, this little washer deserves the same attention as the oil filter. Best practice is to replace it at each oil change. The old washer takes a permanent set, reusing it ups the risk of a weep or seep around the plug. If a new washer isn’t available on the day, inspect the old one closely and only reuse in a pinch, then swap it at the next earliest chance.

• Fit type: typically a single-use crush washer for the Lancer’s M14 oil drain plug on 4B11/4B12 engines. Confirm by VIN/engine code.
• When to replace: every oil change, or any time the plug’s removed.
• What to watch for: oil mist or drips at the plug, washer visibly grooved, nicked, or flattened unevenly.

When refitting, clean the sump face and plug flange, fit a fresh washer, and tighten to the factory torque spec rather than “by feel”. Avoid stacking two washers and steer clear of thread sealants—neither is needed when the correct crush washer is used. If the sump has been previously overtightened or the plug threads feel rough, have a technician inspect for thread damage and replace the plug if required.

Choosing a quality washer—aluminium or copper to OE spec—keeps the Lancer tidy under the carport and the engine happy. It’s a low-cost part that does a big job, the kind of simple preventative maintenance that pays off every time the oil gets dropped.

Popular questions about 2015 Mitsubishi Lancer sump plug washers

What size washer does a 2015 Lancer use?
Most 2015 Lancer petrol models with 4B11/4B12 engines use an M14 crush washer. Variations can exist by market and engine, so it’s smart to confirm against the VIN or an OE parts listing before buying in bulk.

Do you really need to replace the washer at every service?
Yes—crush washers are designed for single use. Replacing it at each oil change helps avoid slow leaks and means the plug can be torqued correctly without over-tightening.

Can a reusable bonded washer be used instead?
Some aftermarket bonded-seal washers can work, but the OE approach for the Lancer is a single-use crush washer. If opting for reusable, match dimensions exactly and check for seepage after the first heat cycle.