View of woman chemist testing used motor oil samples for dilution by water or gasoline. Stands hold glass test tubes and flasks. Burners in foreground. Typed on front: "DL-G-2000, G.M. 73703-121." Typed on back: "The life of vital engine parts depends to a large measure on good lubrication of the working surfaces. Here, a research chemist checks used motor oil samples for dilution by water or gasoline."