Mix oil and sugar until blended, add eggs one at a time.
Add the pumpkin to creamed mixture.
Sift together the flour, spices, soda, baking powder and salt and add it to the creamed mixture.
Stir in the pecans.
Pour batter into a tube pan that has been lightly sprayed with a non-stick cooking spray and the bottom of the pan lined with waxed paper.
Bake the cake in a preheated oven @ 350 degrees for 1 hour and 15 minutes.
Remove from oven and let the cake cool in the pan.
Melt the butter in a saucepan over medium heat.
Add the sugar and bring to a boil stirring constantly. Boil for 2 minutes.
Add the milk and stir until it returns to boiling.
Remove the mixture from heat and let cool.
When mixture has cooled, add the powdered sugar and beat until mixture is creamy.
Spread icing on top of cake and let it drip down the side of the cake.