Grease and flour a 13x9 cake pan.
Preheat oven to 350.
In a saucepan, bring 1/2 cup butter, 1 cup Coke, and oil to a boil.
Combine flour and sugar. Add to saucepan and beat.
Remove from heat.
Add remain cake ingredients. Mix well and pour into prepared pan.
Bake fro 30 minutes or until toothpick inserted in center comes out clean.
Cream butter and 1/2 cup cocoa in a large bowl.
Add in 1/4 cup Coke, chocolate syrup, and 1 tsp vanilla.
Beat in powdered sugar 1/2 cup at a time, scraping down the sides frequently.
If frosting is too dry, add a little Coke to thin.
Frost the cake while it is still warm.
Serve with Vanilla Ice Cream.