I think you're hosed, at least as far as the clothes go. I've gotten
splashes of vac oil out of jeans by just soaking in soapy water,
rinsing and repeating, but that wasn't for the type of soaking
you're describing. I'll share a secret though: ultrasonic cleaners.
I've gotten soy- sauce & blood (not at the same time) out of kakis by
dunking the area into the ultrasonic, and letting it run for 15-20
minutes. Just using my standard buffing-compound remover solution. I
imagine a more 'appropriate' solution would probably do a better job.
If you have an ultrasonic cleaner, I don't think you've got much to
loose by experimenting.
As far as the flasks go, if you got them above 1260, there's no
carbon left on them, so there shouldn't be anything to worry about.
Vac oil has some weird stuff in it, but it shouldn't survive that. If
you're really concerned, get some scotchbright pads or wheels on the
buffer, and have at the inside of your flasks. If you get through the
oxide coat, and back down to bare metal, you've removed anything that
could possibly have been there. (overkill in my view, but it is the
ultimate 'yeah, it's gone.')
For the ceiling? Replace the sheetrock when you move. If it's your
studio, you're going to have to gut it anyway. Don't worry about it
The good news, such as it is, is that the whole thing that makes vac
oil special is that it's designed to have a very low vapor pressure.
Which means that the oil that's hiding in the corners isn't going to
be outgassing weird and unpleasant substances into your shop. It's
messy and nasty, but it's not actively contaminating your air.