A leaky oil drain plug can be caused by several issues, most of which are accessible to the moderately experienced DIY car owner. Oil is vital to the health of your vehicle, and quickly repairing a leak can save hundreds or even thousands in repair bills down the road.
Step 1 - Determine What Is Needed
Be certain to properly identify the problem before beginning any work, to save on time and money. It's possible that at your last oil change, a washer or plug gasket was not replaced. Refer to your car's maintenance and repair manual to determine what washers or gaskets are supposed to be in place. You may also simply need to tighten your filter or drain plug.
Step 2 - Remove the Plug
To check for damaged or missing gaskets or washers, it's probably necessary to remove the plug. Treat this like an oil change; prepare a pan for the oil, and have fresh oil on hand to replace it. Jack up your car and make sure that it's secure, then slide underneath. The oil drain plug is beneath the engine; check the manual again for specifics.
Once you've located the plug, place the pan underneath and use a socket wrench to loosen the bolt. Finish the removal process by hand, staying out of the way of the oil that will run out.
Step 3 - Check for Missing or Damaged Parts
When the oil has finished draining, wipe off the hole and the plug with a rag. Be careful to keep track of the plug, or you may have difficulty replacing it with one of the same size without a reference. You should now be able to see whether or not your washer or gasket is damaged or missing. Look for cracking on rubber, bent metal on washers, and stripped threading on the plug itself. Any of these deficiencies could cause a leak.
Step 4 - Repair or Replace Needed Parts
Once you've identified the damaged or missing piece, replace it. If the plug looks worn, but the threading is mostly intact, a new plug of the same size should do the job. Washers should be carefully placed around the plug's thread and screwed into the mounting. If the thread on your plug is stripped, use a slightly larger plug to prevent future leaks. Use the owner's manual to insure proper installation of any gaskets.
Step 5 - Replace the Plug
Screw the drain plug back into its mounting. Consider replacing the oil filter while doing this task, as a new oil filter is the only thing missing for this to serve as a complete oil change. Open the hood of the car and refill the oil that was removed during the process. Leave a clean oil pan under the drain plug overnight to be certain that the leak is resolved. If it is not, you may need to take it to the mechanic to repair damaged threads using special tools.
The great part about this process is that you can repair a leaky drain plug and get an oil change without any additional labor!