think these products are OK to a certain extent but there are products out there better than penetrating fluids that can take more than a week to soak in ,, a fiend of mine that has worked around the world in different restoration businesses showed me this type of product that freezes bolts nuts ,, I've used a type of this liquid "freezes to a lower temp" to free seized door hinges ,,,,,,,,
now if you use a freezing spray , then use a penetrating spray it should come free with ease ,,
I've also used it on seized engines after them not coming free after filling bores with petrol and setting on fire , but if after filling bores with petrol setting on fire the engine still does not move try spray the pistons with freeze spray while the cylinder liners still hot then it should come free ,, check the link below
Ambersil 6150003601 New! Rust Flash Rapid-Freeze Rust Release Spray 500ml
Prices from: £2.29 each (when you buy 48)
Seized fasteners don't stand a chance with Ambersil Rust Flash.
An advanced formulation based on the laws of thermo-dynamics which rapidly freezes rust down to -40°C causing micro fissures to form in the rust layer. The micro-fissures ensure the active penetrating ingredients get to work deep into the thread, and allow the fastener to be removed up to 10 times faster than ordinary penetrating formulations.