Haha. Yep. WD-40 is petroleum distillates and for DIY noobs.

Penetrating oil for not hot work: 90/10 vegetable oil + acetone. Much better than commercial products and very cheap. IIRC it was tested on ProjectFarm (I maybe mistaken) and written up in a Drexel paper. [0]

Machinist's Workshop - April/May 2007 says 50/50 ATF + acetone, which requires mixing before use.

0. https://www.engineeringforchange.org/wp-content/uploads/2015...

If you want to stop a squeaky hinge on a exterior gate, a very thick oil like axle grease would be best.

For indoor use, like on a door hinge, graphite should be tried first since it won't make that much of a mess.