Trying to guage which size UNO/Poxy to purchase--16 OZ ONO/8 OZ Poxy or 32/16. I know everything is dependent on the paint/condition etc and that a little goes a long way, but--will be polishing my two cars which are in pretty good shape plus 2 others that will need a little more work. I just don't want to buy so much that it is sitting on the shelf forever.