Is my oil pan drain stripped?

Question

2008 BMW 328i, aluminum oil pan.

Changed the oil myself for the first time on this car. When I put everything back together the drain plug is dripping slowly. I go back under the next day to tighten the bolt and ... it sure seems like it's stripped. Spinning around.

On the other hand, this is my first time using a crush washer, so maybe I didn't tighten it enough?

It's still dripping slowly.

What should I do?

(And by the way, is draining the new oil, experimenting with the plug, and then re-filling car with the same oil a terrible idea?)

Update: I ended up taking this to my mechanic. They determined that while the drain plug screw is about an inch long, the thread in the oil pan is twice the depth, and only the outside was stripped. They replaced the screw with a longer one and I'm back on the road for under $30. Lucky!

Answer 1

When tightening a drain plug with a crush washer, you will feel the resistance as you contact the washer and begin to crush it. Once you have reached the appropriate sealing torque, you'll feel the resistance increase substantially.

If the threads in the oil pan were damaged and you had to fight resistance caused by the damage, you might not have detected the change in torque. An undamaged threaded hole should have very low torque requirements for initial insertion. It can be low enough to spin by hand, but once you hit the washer and beyond, it's wrench territory.

A bit of research on your vehicle shows that the aluminum threads are prone to failure and are frequently replaced with steel inserts designed for this application.

One resource includes the clearly written instructions for installing an insert, which would be purchased along with the cutting tools necessary for the job. I would note that it appears necessary to remove the oil pan to ensure no cutting debris would enter the lubrication system during the insert insertion.