oil makes moister cakes. stick with it.

I use 1/2 c oil, add a box of pudding, 1 c of water and 4 eggs and always get at least 24, if not more.

I get 18 but I fill a little more to get slight muffin tops.

I usually add a box of dry pudding mix (just the powder) to the cake batter. It gives you a moister cupcake and usually adds just enough to get the full 24 instead of 22 like the pp. it is also an easy way to add a new flavor. Banana pudding added to a yellow cake mix gives you banana cake. Throw in a half a bag of mini choc chips and now you have chunky monkey cupcakes. Yum!
I never swap the oil for butter. Some mixes call for butter but I think the mix is slightly different.

Butter has a different melting point and consistency, so it can change the baking time to switch them. I usually don't bother.

No, use the oil. I find that I get 22 out of a box.

Thanks! That is helpful. Know anything about oil v. butter?

Depends on the size of the cups! WHat cake mix is it? If it makes 2 9-inch rounds, then it usually makes 2 trays of cupcakes. Remember only to fill them 1/2 full.

Do the boxes usually make 24? Very unclear from the box how many cupcakes it makes. Also, do you recommend substituting butter for oil?