I use a rather large (8" x 10") four layer cotton flannel pad which holds quite a bit of oil. What I do (and what I've read that others do too) is after each use, fold it up and slip it into a plastic bag (I use a zip-lock bag) and store in the refrigerator. It will keep for many months this way. However, have found that I can't be stingy with the oil and add a tablespoon full or two with each use. If I don't the results aren't nearly as beneficial. Trying to wash this cloth would be next to impossible and might even damage a washing machine due to the heavy nature of the oil.
Question that was asked:
Does one really reuse the sodden cloth again and again? I've been trying to wash it in water and its real difficult to get the oil off it.