How much applesauce do you use in place of oil?

Yes, I have done this several times, and I see little difference between using oil and Applesauce. Couple of things to think about beforehand.

1. Use unsweetened Applesauce, otherwise adjust your sugar amount, sorry I don't know how much, as I always used unsweetened.

2. The oil helps somewhat to keep things from sticking, I always use parchment paper for baking, trust me, its awesome and its in the foil/plastic wrap section, and can be used for almost anything up to 450 degrees Fahrenheit that you don't want sticking

3. I tend to use 2 times more Applesauce than oil, again the unsweetened kind. I have also cut the oil amount in half, and used the Applesauce x2.

I am not a professional by any means, baking is more about chemistry than anything. I recommend playing with the amounts a bit before showing off your healthier cake. Hope this helps!