A 50/50 mix of acetone and automatic transmission fluid will beat both of them hands down.
WD40 is great for surface rust protection on tools, saw blades, and pretty much any implement made of metal. It’s also fine for “better than nothing” thread/nut assembly/disassembly. I’ve sprayed it into the innards of outdoor combination locks, keyed locks, door hinges, etc, all with good results. It’s great for locks because it’s so light, it doesn’t gum them up. I know people say you should only use graphite in locks, but I’ve sprayed a lot of sticky locks with WD40 and never had one gum up.
It’s not intended to work as a penetrating oil or a " real" lubricant, and as long as you understand that, there are a thousands of uses for it.