Why do i have rust looking fluid in radiator and rusty spark plugs

What is your question?

So I took my car in to get a tune up. They guys said my spark plugs were rusted and injectors were gunked up. They changed the spark plugs wires, cleaned the injectors and everything else. Then I took my car in to have the radiator changed out again (due to faulty manufacturing) they said the fluid looked like rust color almost a milky substance. Is this my head gasket? I also have fuel in my oil :(