My 1980 DL with a manual transmission is impossible to remove the lower transmission drain plug. It's square shaped. Thus far, I have tried: Liquid Wrench; pressure washer with water; channel lock pliers; crescent wrench; Gator Grip (broke the Gator Grip!). I lubricated the bolt and worked it back and forth, all to no avail.

Mike,

As has been posted ... if it moves but won't thread out you may have a cross thread problem. Try some PB B'laster (Walmart and many auto supply stores carry it ... you should have some anyway ... the best for freeing corroded fasteners)Then take a pipe wrench to it. I've never had a tranny plug not come free when using a P wrench. You may need a new, possibly over size plug and you may need to cut some new threads in the tranny case. Good Luck.

You say you have worked it back and forth a bit. You mean it will move, but then jambs? That sounds serious, as if the thread is damaged or a bit has broken off.
Normally, if it is just tight, then if you can get a grip with anything and apply enough force, it must move. As a last resort I have heard of welding on a metal bar.
You could try cleaning up 2 of the burred flats with a grinder so that a wrench will get a new grip.

Timne to call on Dr Acetylene. Heat it up a little and it will come out. If it doesn't start the first try, heat it up again and put the beeswax to it. The wax will wick in as the plug cools. Great lubrication.

I kinda hate to ask but have you tried the right sized wrench with maybe a pipe or another bigger wrench over it for leverage? And if the corners are so gone on it that the wrench won't hold, try a big pair of Visegrips?
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total

Yup, I meant Vise Grips and not channel lock pliers. Didn't work. Right size socket nearly stripped the bolt.