I had the same problem changing the gear oil on my 1985 bmw 535i. I finally got it out with a hex key from sears that a friend cut about 2" off with an electric grinder. We then used a 2 foot pipe on the end of it to get enough torque and also used a wood plank pressed against the tool to keep it from popping out of the plug. We still ruined the plug and had to replace it. The replacement plug from bmw was different (i guess lots of people had the same problem).