If you replace all of the oil with applesauce (unsweetened), you will have a wonderfully moist cake and will not miss the oil at all. I have been doing this for decades and I am always complimented on how moist the cakes are.

Thank you so much!

Diet soda cakes come out great.  You CANNOT tell the difference.  Use one 12 ounce can of diet soda to a regular cake mix (just be sure to mix well with an electric mixer) and bake according to the normal instructions on the box.   Use cola for dark cakes, lemon lime or citrus sodas for light colored cakes. You can jazz up your cakes by using flavored soda (like diet cherry cola cake, etc).  Your imagination's the limit!

I did that for my fathers birthday. I made a diet 7up strawberry cake with homemade dark chocolate (unsweeted) topping (candy bar with soja cream melted together). Everyone said it was really good...and moist.

But even when I do it the normal way I never add oil...cant stand oil. I would just add more water or milk...whatever else it called for.

When I make cake from a mix I just ignore the oil thing entirely.  When I was a kid, cake mix didn't call for oil so I figure it can't really be necessary.  I remember the first time my mother got a cake mix that called for oil and she was flabbergasted.

Anyway, I put in as much water and egg (I use egg substitute) as it calls for, and then enough extra water to make the cake mix the right viscosity, which is usually somewhat less than whatever amount of oil it calls for.  It tastes the same, it's just maybe a little bit more delicate to handle when putting it on the plate etc.