Pour olive oil in the bottom of the slow cooker liner or spritz with nonstick cooking spray.
Place beef roast in the crockpot with the fatty side up so the fat drippings baste the roast as it cooks. Rub onion soup mix into all sides of the roast. Pour red wine vinegar and liquid smoke over seasoning. Cover with lid.
Cook on low for 8 hours or until fork-tender.
Remove roast from slow cooker. Pull apart roast using two forks.
Add barbecue sauce to the roast and stir to combine. Serve.