2011-16. 3.5 LITER. Oil pipe union. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure the Engine Oil Cooler Line Fitting to it's mounting point. A threaded rod with a drive head (such as hex, 12 point, torx, etc.) on one end used to secure the Engine Oil Cooler Line to it's mounting point. Engine Oil Cooler Bolt. Line Connector. pipe.