Originally Posted by JHR
Special socket - check.
Torque wrench - only to check how much torque I was putting on the stuck plug...after trying to remove it with the socket wrench, extension, and special BMW socket.
The penetrating oil should work from multiple sources. Thanks,
I understand what you were trying to do, but torque wrenches don't work in reverse (they do work for torquing left-hand fasteners). There is no reason to try and measure the torque when removing a plug or fastener, it has no relation to how much torque was applied to the plug (or fastener) when torqued down. Like someone else said, if the plug was put in incorrectly previously by being cross-threaded, then the damage is already done. Penetrating oil may work (plugs are sealed to the head to prevent combusion gas leakage), but it may not reach the threads. Just get the biggest wrench you can and get the plug out and see what is what. I doubt you'll break the plug. It's a steel plug body threaded into an aluminum head, you'll pull the threads out first. Good luck.
For example, I have removed O2 sensors that required a 3 foot extension on my 28 inch breaker bar, and the O2 sensor remained in tact.