An elongated socket tool includes a tubular socket member having a cavity for receiving a hexagonal threaded fastener and a drive member having a recess for receiving the square drive stud projected from a torque wrench. The socket member and the drive member are welded to opposite ends of a tubular metal body which also defines a chamber for receiving a marking fluid. A flow restrictor plate is welded between the body and the socket member and has orifices which control the flow of marking fluid from the chamber into a cylindrical wick confined within the socket member. A removable flexible cap normally covers the socket member when the socket tool is not in use.