Stubborn Oil Drain Plug

I am having difficulty removing the 11/16th inch square oil pan drain plug (part 750 273 M1) from the pan of my TO-30. Is there a special wrench available? My typical hand wrenches (combination and crescent) combined with penetrating oil and tapping with a hammer haven’t been able to do the trick. I am afraid of rounding the plug edges any further. And the very shallow clearance between the top of the plug and the case prevents the use of my ratchet and sockets. Do you have any suggestions?

All I can recommend is brute force. I’ve found that a large crescent or adjustable wrench with nice tight sharp jaws works well, or a good open end wrench with no wear. The penetrating oil and tapping the end of the wrench with a hammer will also help to break it lose. New drain plugs are available but the copper gaskets are kind of pricey.

I’ve know people to weld a hex nut onto the plug to get a better grip with a wrench. That’s not easy to do but, it can be done. Someone put it on too tight I suspect, possibly because the gasket was leaking.

Another option is to remove the oil pan. Wear old clothes, put down some oil dry and get someone to help because it’s hard to balance and hold the pan up when it’s full of oil. Once removed you can turn it upside down on your work bench or other flat surface and use a socket for square head bolts in an impact wrench to remove it. The ratchet like banging of the impact can free just about anything. If the corners of the plug get rounded off, weld a nut to it and use the impact to remove it.