Preheat your oven to 325F.
In a small bowl, combine the brown sugar, paprika, garlic powder, salt, black pepper, onion powder, oregano, cumin, and chili powder.
Place the Boston butt on a roasting pan. Rub the olive oil all over the pork.
Apply the spice mixture evenly on all sides of the pork, pressing gently to ensure it sticks.
Cover the pork with foil and put it into the preheated oven.
Roast for approximately 4 to 5 hours, uncovering the foil during the final hour. Cook until the meat is tender and the internal temperature reaches 195F.
Remove the pork from the oven, cover it with foil, and let it rest for 15 minutes before slicing or shredding.