The short answer: NO. You might get a week or 3 out of it but basically NO. Those pour in to restore products are what they used to call Snake Oil. (At least all the ones I've seen)
it is possible, but it takes a process,, And that takes a battery rebuilder.
They basically clean it, chemically treat it using a multi step process, and other wise make it new again. But it is not something you can pour in.
NOTE: Since the six volt batteries used in an RV are really half of a 12 volt battery.. This applies equally to 12 volt batteries (both halves, separately or together).