Rust under factory paint

Its just on the surface i sent the pics to a very reputable car restoration shop they told me most old cars have rust patches under the factory paint they gave the same advice as you guys did with the rust convertor they use por 15s metal prep and ready its like ospho but you only have to leave it on for 30 min. it leaves a zinc coating over the metal that they told me to sand away then put etch primer or epoxy primer over it i finished it up yesturday it seems to have worked good I will let you know if the primer falls of LOL