edit: Donβt do this. Embrace modernity and donβt pollute the soil.
Thereβs a lot of plant based oils you can use, without additives, that give excellent weather protection. Choice of wood is also a huge factor.
Tbh Iβd rather replace my fence every five years than cake it in used motor oil.
Iβd rather spend $2 on diesel and free used oil than thousands replacing my fence constantly.