Wool Fat = Anhydrous Lanoline
Your local chemist will stock it in BP grade. It’s getting a bit expensive these days but unless you are younger than 50 years old a 500g tub will see you out as only a thin smear is needed, it goes a long way.
It is enormously useful for all sorts of wet proofing or rust preventing jobs. For example smeared onto exposed parts, a car’s brake pipes for example; it develops a skin that is proof against anything the roads can throw at it. I first found about it when sailing and anything that can resist seawater has got to be good!
On threads, particularly ones that will be regularly undone, it will prevent seizures while being sticky enough to discourage loosening due to vibration.
A thin layer inside a mudguard will do much to protect the paint particularly by the time it’s collected its inevitable layer of road clag. Nature’s own stone chip protector!
It even has a DIY use around the house, dip a woodscrew in it and it drives in much more easily, makes a better thread in the wood thus a better grip and stops them going rusty in the wood too.
As I’ve said on here before: When you last see a rusty sheep?