Heat oil in a large skillet over medium-high heat. Brown the roast on all sides in the hot oil. Remove, and transfer to a slow cooker.
Sprinkle onion soup mix over the roast, then pour in the apple juice. Cover and cook on MEDIUM for 6 to 8 hours, or until meat is very tender. Check occasionally to make sure there is sufficient liquid, and add more juice if necessary. Serve roast with juices, or thicken them for a tasty gravy.