There are some good spray chemicals available at places like auto parts stores. By the way, WD-40 is good for a lot of things but not for this. Just go to your store and read the cans, looking for one that offers help for what you are doing. If this doesn't work, there are tools like nut busters, hammer and chisel, hacksaw, cutting torch. What you are working on, and how much you need to save will determine what to use. If all else fails, use a bigger hammer.