ATV Leaking Oil Drain Plug (Easy fix!)

Finding black drips under your ATV can be worrying. The best you can hope for is a leaking drain plug, so I guess maybe we’re getting lucky here.

So why does the ATV oil drain plug the leak? The top 3 reasons an ATV drain plug leaks oil include:

  1. Missing plug washer
  2. Worn out crush washer
  3. Over-tightened plug

In this post, you’ll learn why your ATV oil drain plug leaks oil and what you can do to fix it today.

Oil Change

After an oil change, it’s always good practice to replace the oil plug washer. I’ve been a mechanic for more than twenty years, and I’m plenty guilty of reusing the same oil plug washer when needs must, but doing so simply won’t guarantee a dry pan.

An untreated weeping oil plug, as you know, coats the underside of your bike in oil, and airflow pushes it back ways coating the rear end in a slick.

A leak is irritating but could also be a safety issue, as oil could contaminate the rear brakes and tires.

The other glaringly obvious hazard is running out of oil and granading the motor.

You are absolutely correct. This oil leak needs to be fixed.

Missing Washer

A missing washer is a common mistake to make, your changing the oil, and the old washer drops into the waste oil, either unnoticed or forgotten.

Either way, the net result is a wet pan.

The simple fix here is to fit a washer. If your oil is fresh and you want to save it, be really sure the underside of your bike is clean before dropping it into a pristine container.

Crap falling into the oil is a BIG NO NO.

Worn Out Crush Washer

Washer types and materials vary. Crush washer, copper, alloy, rubber o-ring, and some may use pipe dope.

All wear out, but the crush washer causes the most issues when reused. It’s one-time use only.

How does a crush washer work? As its name suggests, the doughnut-shaped ring washer is crushed as the plug is tightened. This creates a tight seal but using it a second time risks a leak.

Copper and alloy washers are far more forgiving, but obviously, they wear out too. Copper and alloy are chosen as they’re soft metals and conform to the plug and pan faces.

The rubber o-ring seal is popular too and is susceptible to damage.

Pipe dope is used on some motors. A mechanic may use pipe dope to seal threaded plugs. It’s a liquid sealer that prevents oil from leaking through plug threads.


Over-tightening plugs are the cause of many a problem, and like a young apprentice, I was guilty of that and a lot worse.

Over-tightening any of these washers may cause them to leak. Manufacturers will have a torque speck for the plug, but you need common sense.

The more you work on your bike, the faster you’ll develop a calibrated thumb.

A bung needs to be snug, not lug wheel tight.

You may find these posts helpful also:

Will dirt start without oil?

ATV coolant in the oil

ATV oil leaking from the exhaust manifold

John Cunningham

John Cunningham is a certified mechanic and writer on I’ve been a mechanic for over twenty-five years, I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of ATV ownership, from maintenance & repair to troubleshooting.

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