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Is Gumout safe for yellow metals? I.E. Copper Fuel line? Is Gumout safe for a diaphram style fuel pump with a neoprene diaphram? Is there a gumout product specifically designed for cleaning out fuel lines/fuel tanks that have long since been “Dry” — as in the issue is less because of gelled gasoline and more grease, dirt, oil possibly that have entered unsealed parts of the system over time?