In a large bowl cream together oil, sugar, and eggs.
Then add remaining cake ingredients and mix until well blended.
Pour into a greased 9 x 13 inch baking dish. (I used a glass pan)
Bake at 325℉ for 45 minutes.
Cool completely on a cooling rack before frosting the cake.
After the cake has cooled, mix the powdered sugar, butter, cream cheese and vanilla in a separate bowl until smooth and creamy. Spread evenly over cake.
Notes
You can substitute butter or shortening for the margarine in the cream cheese frosting.