Generally it is not a good idea to use mayonnaise in place of vegetable oil just because of the fact that its taste will most likely conflict with that of the other ingredients you are using. Instead it will be important to think about using something else that will not affect the dish so much.

While it is true that some people decide to use mayonnaise instead of vegetable oil in some recipes, there are definitely better substitutes that you should look into before making a final decision as to what you should use. If you do choose to use mayonnaise in place of vegetable oil it will be important to choose a light variety so as to reduce the amount of fat that goes into the dish you are making.