I have the same problem on my 1997 Trooper. Bad design with steel-threaded plug in aluminum-threaded case. Particularly when dealership workshops don't treat them with due care.

Because it's only the filler plug, I used a liquid thread repair to create a substitute thread. When inserting the plug I apply silicone gasket seal on the plug thread and then finger-tighten it. This has worked OK for several years now.

I have also read a suggestion of using teflon plumbing-thread tape (it is a fine, white, non-adhesive tape here in Oz).

Last edited by boritz; 07/30/07 02:18 AM.
Aussie 1997 3.2V6 SOHC 6VD1 Holden Jackaroo SE (Isuzu Trooper/Bighorn/Monterey) 5-speed manual, rear LSD, front Lokka (manual free-wheel hubs).