Preheat oven to 325°F. Spray pans with vegetable pan spray.
In medium bowl, combine flour, baking soda and salt.
In separate bowl, whisk together oil, buttermilk, eggs, vanilla and rum extract. Stir in sugar, pineapple and, if desired, nuts.
Add flour mixture; mix well. Pour into prepared pan.
Refer to baking chart in techniques section for baking times and temperatures for specific pans.
Cool 10 minutes in pan on rack; remove and cool completely before decorating.
Makes about 5 cups batter.