Engine Oil Cooler
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The engine oil cooler (EOC) is an auxiliary heat exchanger located on the left rear side of the engine. Numerous cooling plates inside the EOC help to dissipate heat and control engine oil temperature.
The engine oil pump forces the engine oil through the EOC cooler through an inlet pipe. The engine oil then flows through the EOC where heat is dissipated from the fluid back to the atmosphere. The engine oil is then pumped through the EOC return pipe, back to the engine.