It's always been called Max on the labels. However the characters always call it MOx.
The O is supposed to be censure, like M*x, for example. It just looks fancy because only one letter got replaced and it doesn't look that much like censoring. So, as the Zerud guy said, they don't censore it when it's just "Max", but they have to do it when it's "Max Coffee".
You...idiot!Marisa doesn't know I bought it.Uh-huh...Hyaaa!Here! Drink this!Energy SourceKeep your chin up.Ah...Don't cry.