In a medium bowl, combine the oil, vinegar, garlic, Worcestershire sauce, white pepper, salt, black pepper, and sugar. Mix until everything is combined.
Add the poultry seasoning and celery salt and mix again to incorporate all of the ingredients.
Place your chicken pieces in a shallow, non-reactive dish (such as a glass or ceramic baking dish) and pour the marinade over the chicken. Cover with plastic wrap, and place in the refrigerator for at least one hour to allow the flavors of the marinade to penetrate into the chicken.
Preheat your oven or grill to 375°F/190°C. Remove the chicken from the marinade and discard any unused marinade. Place the chicken on a baking sheet or grill, and cook until an instant-read thermometer inserted into the thickest part of the chicken reads 165°F/74°C (about 30 minutes in an oven).
Your delicious Chiavetta’s Chicken Marinade is ready to eat. Serve in a nice dish with your favorite sides.