what is the best way to clean the light rust scale and crud from the inside of a gas tank ? it has been sitting empty for a little while. now i am getting rust or some thing stopping up my fuel line now that i have put it back in service. i can take the fuel line loose from the fuel pump and blow backward into the tank and unstop it.my tank is still good and solid and i just want to take it out and clean the crud out but don't know what to use or where to take it . can a radiator shop clean it?