You reach for the butter when cooking, just like you’ve done so many times before. You’re out of butter or you want healthier less saturated fat use a mild flavored vegetable oil like Canola. Follow this chart

1 tsp. butter                     ¾ tsp. oil
1 tbsp. butter                   2 ¼ tsp. oil
2 tbsp. butter                  1½ tbsp. oil
¼ cup butter                   3 tbsp. oil
⅓ cup butter                    ¼ cup oil
½ cup butter                   ¼ cup plus 2 tbsp. oil
⅔ cup butter                    ½ cup oil
¾ cup butter                   ½ cup plus 1 tbsp. oil
1 cup butter                     ¾ cup oil