Best Pentrating Oil

My technique for stuck fasteners; spray, tap lightly with small hammer, re-spray. Continue. I have gotten 1 1/4" galvanised shackles which were entirely covered in rust apart using this method and a couple weeks of patience.
Look for penetrating oils which contain tri-flo (can't remember the un-contracted name of the solvent anymore.)
Looking forward to trying acetone/hydraulic oil.

I switched to Kroil a few years ago, best thing i ever used. I always keep WD-40 around for cleaning grease and adhesives.

I'll second that!

Had an old timer tell me they use to get broken off exhaust manifold studs loose by heating the stud and then touching a candle to it, drawing in the wax. Never tried it.