Oven Method: No added liquid necessary. Slow cooked pork in the oven will make its own pan juices. So, there is no need to add liquid. In fact, you will need to drain off the liquid pan juices into a container to save for later so that they do not dilute any BBQ sauce. These pan juices can also be added back later to keep it moist. Crock Pot or Slow Cooker Method: Add 1 cup of water to the crock pot before cooking.