Rub ribs with oil. In a small bowl, combine the brown sugar, paprika, pepper, garlic powder, onion powder and cayenne; rub over ribs. Wrap in a large piece of heavy duty foil. Seal the edges of foil. In a small bowl, combine barbecue sauce and beer; set aside. Grill ribs, covered, over indirect medium heat for about 1 hour. Carefully remove ribs from foil. Place over direct heat; bast with reserved sauce. Grill 20 minutes longer or until juices run clear and meat is tender, turning once and basting occassionally.