Parts for your 2004 Mitsubishi Lancer-Sump plug washers

2004 Mitsubishi Lancer sump plug washers — what they do and when to replace

Technical sources confirm the 2004 Mitsubishi Lancer does use a sump plug washer. The Mitsubishi Lancer (CS/CK) Workshop Manual (Lubrication section) specifies a replaceable drain plug gasket during oil changes, the Mitsubishi ASA electronic parts catalogue lists an oil drain plug gasket for 2004 Lancer engines (commonly referenced as MD050317 for many 4G-series engines), and aftermarket service guides like the Haynes Lancer 2003–2011 manual advise renewing the washer at each service. So yes—this part is relevant and fitted.

On a 2004 Lancer, the sump plug washer is the small, easily overlooked hero that keeps engine oil where it belongs. It sits between the sump (oil pan) and the drain plug head, and when tightened to spec it “crushes” slightly to seal out leaks. Most are aluminium or copper crush washers matched to the drain bolt size used across the Lancer range of that era.

Because crush washers deform to create a perfect seal, they’re designed as single-use items. Reusing one can lead to weeps around the plug, oily spots on the driveway, or worse—over-tightening the plug to chase a seal and risking damaged threads in the sump. Best practice on a 2004 Lancer is to replace the washer at each oil change interval. If you service by time or distance (whichever comes first), pop a fresh washer on with every oil and filter swap. Keeping a small pack of the correct size in the glovebox or tool drawer makes life simple.

Handy tips for a tidy job on a Lancer service:

• Confirm the drain bolt size for the specific engine variant, many 2004 models use a 14 mm bolt that pairs with an OE-style washer. VIN or engine code lookup will verify the exact washer spec.
• Clean the mating face on the sump and the plug head before refitting. Any grit can create a leak path.
• Always tighten the plug to the factory torque spec from the workshop manual. Don’t “gorilla” it—let the new washer do the sealing.
• If the plug or sump threads look suspect, replace the plug and inspect the pan. A magnetic plug upgrade is a neat touch, but still use a new washer.

Signs it’s time to act include a faint oil smell after driving, a damp halo around the drain plug, or a drip forming overnight. A new washer is cheap insurance for a leak-free Lancer and keeps the engine topped with the oil it needs to live a long, happy life on Aussie and Kiwi roads.

Popular questions

What size sump plug washer does a 2004 Mitsubishi Lancer use?
Many 2004 Lancer variants use a washer for a 14 mm drain bolt, but engine options vary by market. The safest bet is to match by VIN or use the OE part number listed in the Mitsubishi parts catalogue for your specific engine. If measuring, match the washer’s inner diameter to the smooth shank of the bolt, not the thread crest.

How often should the washer be replaced?
Replace the sump plug washer at every oil change. It’s a crush-style seal designed for single use. Even if a reused washer seems to hold, it can seep later, so a fresh one each service saves mess and hassle.

Aluminium or copper—does it matter?
Either can work if the size and style are correct. Many Mitsubishis of this era shipped with aluminium washers, while copper options are common and reliable. Some DIYers anneal copper to soften it, but for most owners a new washer of the right spec is the straightforward choice.