It's snake oil. If snake oil comes in solids anyway. Any dolt knows that the lead in gas is/was tetraethyl lead which cannot be made just be soaking some lead pellets in the gas. If some elemental lead dissolves it will not do anything. If it does you will see a buff colored residue in the tailpipe and the next time you report for state inspections you will be tarred and feathered. If there is no buff colored residue there IS NO LEAD in the fuel, and none to do your valve seats any good. But on your modern engine you have hardened valve seats and do not need lead at all.