I would drop the oil pan I know would be a pain. This way you would have more leverage to remove it and not make a bigger mess

good luck

 

How would you have more leverage trying to hold the oil pain? Seriously, get a huge pair of vise grips.

 

huh,thats funny,mine is a16mm on a 04 3.8 and its got a little magnet on the end to see if there are any shavings in the oil.(havent seen any, thank God!)

 

Someone changed it at one point then. GM only uses 13mm and 15mm on everything except for daewoo's, Duramax engines, and cruzes.

 

Not to mention, by not being bolted to the motor, stands a real good chance of bending it, preventing it from properly sealing when put back on.

There have been a bunch of good ideas posted. I think I lean in, a GOOD set of vice grips for the job (as I noted earlier, I know at least 2 different styles and the one probably will not work well for this job).

The other thing, stop putting the plug on monster tight.....

 

And when I'm changing the oil on my 2000 or my parents' 06, I never seem to remember which is which and grab the wrong one. Never fails haha

 

Another thing I have had success with is using a dremel to cut a slot in the head of the bolt, then getting a really big and broad flat head, sticking it in the slot and backing the nut out - just as if it were a flat head screw.

 

snap on and craftsman both make tool sets for rounded bolts. personally i wouldnt heat it or hit anything aluminum with a hammer. bad things happen very quickly, and if you arent careful, you will be replacing more than what you want. most garages could get the bolt off for you and install a new one for a minimal fee, with an oil change. btw. you dont have to tighten the hell out of an oil plug.

 

Here we are, a lot of suggestions and 8 days since the OP posted for help. I think we need a status update from the OP lol