Let me ask this question of the experts. Kind of like the end of leaded gas, if the old oil has been run in an engine for 50 years, will it really hurt the engine to switch on something that gets limited drive time? It would seem that all the zinc you could ever need is deposited all over the parts of the engine needing oil.
Just a thought. On the converse I do add a lead additive every three years or so.
