Combine 1 cup sugar with 1 T. Cinnamon and set aside
In large bowl, mix flour, baking soda and salt. Set aside.
In a small bowl, combine oil and 1-1/2 c. Sugar. Add buttermilk and eggs to oil mixture - mix well.
Stir oil mixture into dry ingredients in the large bowl - just until moistened.
Spray 2 loaf pans with Pam. Fill each loaf pan about 1/3 full of batter. .
Sprinkle 1/4 of the reserved cinnamon mixture over each pan of batter
Top each loaf pan with remaining batter
Sprinkle 1/2 of remaining cinnamon mixture evenly over batter in each loaf pan.
With a butter knife, insert knife into batter at one end of loaf pan, thru both layers of cinnamon, and swirl knife thru batter working down to the opposite end of the loaf pan.
Bake for 44-55 min. At 45 min., check bread to see if it is done.
Cool in pans 10 minutes before taking out of pans. After removing from pans, place on racks to completely cool.
Once loaves have cooled, combine powdered sugar, milk and vanilla. Mix to consistency you can spoon over loaves. Add more sugar or milk to obtain right consistency. Drizzle in zip-zag pattern over loaves.