Rub roast with olive oil. Season liberally with salt, pepper, onion powder and garlic powder. Place into a roasting pan in a preheated 375 degree oven for 2 hours, turning often for even browning. Place roast on foil and coat roast with barbecue sauce. Wrap snugly with foil, place back into the roasting pan. Lower oven temperature to 325 and return roast to oven until meat pulls off the bone easily about 2 – 3 hours more. Allow to cool and pull meat. Shred any large pieces with hands, knife or fork.