In a large bowl, dissolve yeast in warm water. Let stand until creamy, about 10 minutes.
Add the buttermilk, sugar, vegetable oil and flour to the yeast mixture; mix well. Roll dough out 1/2 inch thick and cut into circles with a biscuit cutter. Place a tablespoon of butter on top of each biscuit and fold biscuits in half. Place rolls on lightly greased baking sheets.
Bake in preheated oven for 10 to 15 minutes, until golden brown.