First, you need to determine if it is a Heli-Coil or a solid insert. Then, get a replacement whatever it is and a new plug that fits. I would almost bet that who ever installed it used the wrong thread pitch.
If it is a heli-Coil get one that is self locking. Once this goes in, it will not come out without unwinding it. If it is a solid insert such as a time sert, also get the proper tool to set it. Drain the oil, clean the threads in the case real good and then use loc-tite red to install it. Use fiber or nylon washers as the plug seal and you should be all set.

Dennis

----- Original Message -----
From: Ed Wiebe
Date: Wednesday, February 21, 2007 9:28 pm
Subject: Oil drain problem
To: vanagon@GERRY.VANAGON.COM

> I come to the list with a problem and hopefully a solution.
> The last few times I have changed the oil, when I remove the oil
> drain plug I get the plug left in a Helicoil. In other words
> the helicoil or time sert unscrews with the drain plug. I
> managed to get a plastic type washer over the helicoil thing and
> have put that back in. The drain plug is so tight in the
> helicoil that I can't separate the two.
> The helicoil with the drain plug and washer can be screwed back
> in, but there are always a few drops of oil on my driveway after
> a drive.
> I'm sure it is just a matter of time before the helicoil will
> strip the thread in the block and that's not a good thing!
> What is the best way to proceed to get a permanent solution?
>
> Ed Wiebe
> 1990 Westfalia
>