Preheat oven to 350°F.
Combine flour, oats, brown sugar, baking soda and salt in a large bowl. Stir in butter and corn syrup. Press slightly more than half the mixture into a greased 9 x 13-inch baking pan. Reserve remaining oat mixture for topping. Bake 8 to 10 minutes.
While crust is baking, stir caramel topping, flour and corn syrup in a microwave-safe container until smooth. Microwave on HIGH (100%) for 90 seconds. Stir and continue to heat 90 seconds longer, stirring after 45 seconds. (Mixture should be fully boiling after each interval.) Stir and set aside. Mixture will thicken slightly as it cools.
Sprinkle apples and pecans over partially baked crust. Pour caramel sauce over apples; crumble remaining oat mixture over caramel. Bake 20 to 25 minutes longer until lightly browned.
Cool at least 30 minutes before cutting into bars. Bars can be kept at room temperature for 2 to 3 days. They can also be kept in refrigerator to retain firmness after first couple days.