Many Betty Crocker cake mixes call for butter in the recipe. It is possible and common to substitute oil for butter when cooking a Betty Crocker cake. Essentially, butter contains 80 percent fat while oil is 100 percent fat; replacing butter with oil adds more fat to a Betty Crocker cake mix. Because oil has less saturated fat, it may be a healthier alternative. Olive oil has more nutrients then butter or vegetable oil. According to Amazing Olive Oil, olive oil is a useful substitute for butter, margarine or other oils in recipes. The basic rule for substituting oil for butter is to use equal quantities of these ingredients. When substituting olive oil for butter, use three-fourths of the volume of olive oil. Use an olive oil described as "buttery" to avoid a cake with a bitter taste.
Substitute 2 1/2 tsp. of olive oil for every 1 tbsp. of butter in the recipe. If you use vegetable oil, use the same volume of oil as you would butter.
Measure the oil into a mixing bowl before adding it to the cake mix.
Continue with the instructions on the Betty Crocker cake box.