>I can't see any way to use it all
>before it goes off... that's if it DOES go off

Buttermilk, at least for quick breads, has a long shelf-life, easily
three weeks. Pancakes each Sunday and buttermilk biscuits once a week
should kill a gallon of the stuff within four weekends. If it doesn't,
add bran muffins and Boston brown bread. Recipes for any of these
concoctions are all over the public domain, as well as in (for
instance) the old Joy of Cooking.

Buttermilk is a wonderful cooking condiment; it adds the kind of
creaminess you associate with cream, without the expense, calories, or
cholesterol.

Neil