Heat the oil in a skillet over medium heat. Place the beef stew meat and flour in a large resealable plastic bag, and shake to coat. Transfer coated meat to the skillet, and cook about 1 minute, until browned.
Mix the potatoes, carrots, celery, onion, and garlic in a slow cooker. Place browned beef over the vegetables, and season with basil and thyme.
In a bowl, mix the chili sauce, beer, and brown sugar, and pour over meat in the slow cooker.
Cover slow cooker, and cook 8 hours on Low or 2 hours on High.