Remove most of fat from pork loin. Place roast on platter and cover with barbecue sauce. Marinate 1 to 2 hours in refrigerator.
Preheat oven to 350 Â°F (180 Â°C).
Transfer pork to roasting pan. Cook 1 hour and 15 minutes in oven.
Preheat barbecue at low.
Oil grill. Remove pork from pan and transfer to barbecue grill. Baste with barbecue sauce and season well. Cover and cook 40 minutes. Turn roast over 2 to 3 times during cooking. Baste occasionally with barbecue sauce.
Serve with grilled zucchini.