Fun fact: WD-40 is not a penetrating lube/oil!

Iirc WD-40 = Water Displacement, formula #40

It was originally designed to displace water for corrosion resistance and cleaning. (Edit I think it was originally used for de-icing in an aerospace context?) You probably will never need a single can of WD-40 in your life. Try PB Blaster or Liquid Wrench!