I bought a gallon of the older Black Fire Wet Diamond sealant awhile back. I have heard the the current version for sale on AG is a new formula. Is there a difference between the two? Is my old 1 gallon BFWD obsolete? I would hate having to use something that doesn't give me the max protection/durability as a new formula would give. I might have to go buy the new BFWD if there is such a big diffence.