In a small bowl, whisk together ingredients for the dry rub.
Pat the pork roast dry with paper towels and rub all over with the spice rub. Set into the crock pot.
Pour juice into the pot around the roast, careful not to pour onto the roast and wash off the seasonings. Scatter onion and garlic around the roast.
Cover the pot and cook on LOW (recommended) for 8-10 hours or on HIGH for 6-7 hours.
Transfer meat to a bowl and shred with two forks. At this point you can serve as is, or add a bbq sauce of your choice then serve as desired.
Notes
Storage and Freezing - Leftovers can be stored in the fridge in an airtight container for up to 5 days or frozen for up to 3 months.Reheating - If you have the time, you can reheat the leftovers in the crockpot on LOW for 1-2 hours until warmed. Or for faster reheating, you can spread it out on a sheet pan, add a little liquid (like apple juice), cover with foil and reheat in a 300 degree F oven until warmed (about 20-30 minutes).