Preheat oven to 325 degrees F (165 degrees C). Line a baking sheet with parchment.

Distribute pecans, cashews, almonds, and peanuts over prepared baking sheet.

Bake in the preheated oven for 5 minutes; shake pan to turn nut mixture and continue baking until lightly toasted, about 5 minutes more; allow to cool.

Place nut mixture with salt into the bowl of a food processor; blend until coarsely ground, about 3 minutes. Drizzle peanut oil into nut mixture; continue to blend until a smooth butter forms, about 2 minutes more, scraping bowl with rubber spatula as needed to push nut butter down into the bowl. Store nut butter in the refrigerator.