Rhubarb Bars

3 cups rhubarb

1 1/2 cups sugar

2 tbls. cornstarch

1/4 cup water

1 tsp. vanilla

1 1/2 cup oatmeal

1 1/2 cup flour

1 cup brown sugar

1/2 tsp. soda

1/2 cup oil

1/2 cup margarine

1/2 cup nuts

Dissolve cornstarch in water.  Add rhubarb, sugar, vanilla, and cook until thick.  In a separate bowl, mix the rest of the ingredients.  Mix until crumbly.  Spread 3/4 of mixture in 9X13 pan.  Pour rhubarb mixture over this.  Sprinkle remaining crumbs over top.  Bake at 375 degrees for 30-35 minutes.