Rinse chicken. With a kitchen scissors or a sharp knife, cut either to the right or to the left of the breastbone all the way through. For smaller grills you can cut the chicken into two halves; for larger grills you can leave it as a whole. Pat down chicken with a dry towel to remove moisture from skin. Rub butter over chicken and then rub seasoned salt (more or less depending on your tastes).
Light grill and clean racks. (Remove top rack if needed to give more room for chicken.) Rub oil on racks. Grill chicken with indirect heat by turning off middle burners and leaving outside burners on. Let grill warm up to 400°. Place chicken skin side down on grill 20 minutes. Flip chicken over with skin side up and add a little butter to keep moist. Cook another 20 minutes. Rotate chicken and cook 20 more minutes. With a thermometer, check meat temperature, it should be 165° when ready. Let chicken set 10 minutes before serving. Enjoy!