COOK IT.
Follow the directions on your brine kit to make the brine. Refrigerate until cooled (40°F or less).
Remove the chicken quarters from any packaging and pat dry with paper towels.
Place the chicken in a large freezer bag along with the chilled brine. Remove as much air from the bag as possible, then refrigerate for 24 hours.
When you're ready to grill, preheat your grill or smoker to 350°F.
Remove the chicken from the fridge and the brine and pat dry with paper towels. Lightly coat with oil, then season with BBQ rub on all sides.
Place the chicken on the preheated grill and rotate every 6-8 minutes to ensure an even color and cook.
Use a thermometer to check when the chicken has reached an internal temperature of 155°F. Then, baste the chicken on all sides with BBQ sauce and continue to cook.
Once the chicken has reached an internal temperature of 165°F, remove from the grill and allow to rest for 6-8 minutes before serving.