Cream together vegetable oil, sugar and eggs. Add carrots and pineapple. Sift together: flour, baking soda, salt and cinnamon and add dry ingredients to the creamed mixture slowly. Add nuts and vanilla. Beat well, pour into a greased and floured 9x13 pan and bake 45 to 50 minutes. Check doneness with a toothpick. Serve plain, with an icing of your choice or with a dollop of whipped cream. Icing: Cream together powdered sugar, butter, cream cheese and vanilla. Beat until soft and spreadable.