Mix the oil, sugar, garlic, soy sauce, pepper and salt in a bowl.
Add the chicken and rub the mixture into the chicken flesh. Cover with cling film and leave to marinate for 1 hour.
Heat the grill, rub with oil, then add the chicken when hot. Let it cook for until browned on all sides and chicken reaches and internal temperature of 170 degrees about 25 minutes . If chicken starts to get too dark move off of the direct heat and continue to cook on the cooler part of the grill.