Originally Posted by rawlus
A breaker bar, or breaker bar extended with a pipe is sometimes required. The more leverage, the easier it is.
Do we know if he has a socket that fits a breaker bar.......or if he has the kind of water heater socket that just has the hole in it to insert a screwdriver, like below?
These type above do a decent job, but can also bend/bow if you had to put a bunch of pressure on it (which is hard to do with just a screwdriver as a handle).
A good 1/2 inch drive or bigger, six-point socket (I would use a heavy wall impact type socket) may have to be used on this stuck one.
B47 had good advice about letting penetrating oil soak for awhile.