1. In a small bowl, mix together salt, paprika, onion powder, thyme, pepper, cayenne pepper, and garlic powder.
2. Remove and discard giblets from chicken. Rinse chicken cavity and pat dry with paper towel.
3. Rub chicken with oil then inside and out and under the skin with spice mixture.
4. Place 1 onion into each cavity of the chicken.
5. Place chicken in a resealable bag or double wrap with plastic wrap. Refrigerate overnight, or at least 4 to 6 hours.
6. Preheat oven to 325 degrees F (120 degrees C). Place chicken in a roasting pan. Bake uncovered for 1 1/2 - 2 hours, to a minimum internal temperature of 180 degrees F (85 degrees C). Use meat thermometer to check in the thigh.
7. Baste a few times the last hour if not using a rotisserie.
8. Let the chicken stand, covered in foil, for 10 minutes.
9. Then carve.