[Request] Does McDonalds make more money on a 30 ounce drink by using more ice or more soda?

Had a discussion with my tech last week - he had gotten a large (30 ounce, I believe) Diet Coke from McDonalds but it was mostly ice.

Does a McDonalds make more or about the same amount of money if they make a drink to be mostly ice, mostly soda or an even mix of both? Also, would summertime make a difference since they're likely generating much more ice than the rest of the year since it's so hot outside?

I also mention Diet Coke, because apparently McDonalds has a dedicated machine JUST for regular Coca Cola.