Seafoam and a lot of automotive cleaners are petrol based, which is a non-polar solvent that dissolves non-ionic compounds, such as carbon deposits and oil. Water dissolves compounds that are ionic in nature. If any of the components in the car are polar, then it would dissolve in plain water. Sea-foam could help in freeing sticky rings but doesnt not repair them.
I always use lucas oil stablizer in my honda and toyota. It's great, its thick when cold but nice and viscus like oil when hot. That and seafoam are probably the only engine products I'd trust with my car.