They just hand the stuff out for free? That's nice of them.

My company does that with nitrile gloves.
If I have descent ventilation, I'll heat AND use penetrant after. But, I try not to breathe in too much of the fumes from heated penetrant. So, in winter with the outbuilding doors closed, it's heat... and if that doesn't work, it's penetrant after cooling.
I've also heard guys swear by heating liberally, then touching a candle to the threads. Apparently, paraffin is drawn in and lubricates the threads. I've never tried it, but it sounds interesting. Enjoy your teardown. Good times.