Oil coolers are used on 2007 or even earlier 2.0L and 2.3L models and early V6 models only. Start by lifting the car and jackstands. The second step is to drain the engine coolant and the engine oil and then remove the engine splash shield. In the four-cylinder models (2007 and earlier 2.0L and 2.3L (and early V6), disconnect the two coolant hoses to the oil cooler, loosen the oil cooler mounting bolt and disconnect the oil cooler to the engine block, taking care to install a new O-ring. The reverse process is the installation which involves the installation of the oil cooler on the mounting bolt tightened to the required torque. In the case of 1.5L and 1.6L, loosen the hose clamps with the pliers in order to unconnect the coolant hoses with the oil cooler. Use the Allen wrench to loosen the screw through the center of the oil cooler adapter bolt until it is loose, then remove the oil cooler by removing it out of the engine block and throw out the O-ring. Check the block surface, replace a lost O-ring on the oil cooler, apply a little oil to it and place the cooler in place, tightening the adapter bolt to the correct amount of torque.