I'd spray PBlaster, whack it a couple of times, put a good tight 6 point socket on it w/ a pipe extension, whack it BOTH ways, to tighten AND loosen, spray, repeat a few hours later. But then I don't usually have a torch handy to heat with.
Older ratchets had far fewer teeth. So you had to swing the ratchet in a longer arc to engage the next tooth. In confined spaces occasionally you would need a 12 point socket to get the right leverage. Some bolts you can't get off with a 6 point socket and course tooth ratchet. Which is why 12 point sets were far more common.Ya how many 12 point bolts have you seen in your life. I have seen some in my 41 years. By some. I mean one time.