A method and system of diagnosing a lubrication system of an engine includes determining a lubrication system fault and controlling an engine in response to the fault. The method is operative to first determine a poor state of health for a lubrication system, then determine an oil degradation or lube system fault. In response to a lube system fault, engine operation is altered in order to reduce the negative effects of the lube system fault such as increasing minimum idle speed in response to reduced oil pressure.