Previous to this episode, I have been losing some oil that I could not find the source of the leak. My battery went down, and after having jumped the car the first time the car ran for just a short while, then retried with other car engine on for extra power - which the car finally started after about10-12 seconds of cranking. The car ran rough and the OEM light on dash came on. Felt as if car was running on 6 or less cylinders. No power at all. Took forever to get to highway speed. Installed new battery, the OEM light goes off - I have power now but heavy smoke comes out the tail pipes. Anyone with idea what went wrong and what needs to be done to fix it. Tune up - new spark plugs and wires? I think oil is leaking from a valve cover, but does not look like a lot - nothing shows from the bottom of the engine.????? Will gladly accept any advice on what might be wrong. Thanks Richard