Ordinary WD40 is not a particularly good penetrating releasing fluid; Plus Gas is much better.
The ordinary WD40 was designed as a water absorption chemical for Military Rockets. The reputation as a releasing fluid just comes from their intensive advertising.
The WD40 company makes an alternative product which, as far as I know, is a proper releasing fluid. The mere fact that they make it 'proves' that ordinary WD40 is not much good as a releasing agent.