Heat oil in large skillet on medium-high heat. Add kielbasa in whole ring; cook 3 to 5 minutes per side or until browned but not cooked through. Remove kielbasa to cutting board. Cut kielbasa into 2-inch chunks. Place in 6-quart slow cooker. Set aside.
Mix remaining ingredients in large bowl until blended. Top kielbasa with sauerkraut mixture. Cover.
Cook 4 hours on HIGH, stirring halfway through cooking.