Just a quick question because I know it works:
Last night I needed to make a couple of chinguses (ding-wazzles?) out of O-2, and since I haven't actually hardened any O-2 ever, I didn't have any ATF handy. But I did have some power steering fluid, so I used that. It appears to have worked fine (particularly because the specification I'm working to is "hard", without any, like, numbers).
Any reason not to? Or for the purposes of plunging hot bits of metal into, are they essentially the same thing?