Pour vegetable oil into the bottom of the slow cooker. Place pork roast into slow cooker. Pour in barbecue sauce, apple cider vinegar and chicken broth.
In separate small bowls mix brown sugar, mustard, Worcestershire sauce, chili powder, onion, garlic and thyme together. Pour over roast. Cover and cook on low for 8 hours.
Remove roast from slow cooker and shred with forks. Return meat to slow cooker and let it sit in juices until ready to serve.