I have a 1993 300SE. I believe that the battery is going bad but it has never shown signs of not holding a charge. Before I take it out can someone tell me the easiest way to check to see if the alternator is working properly? Can I just check the voltage output at the battery while the car is running? I know on my Suburban the output is 14.2 volts but when I tried this on the Mercedes I got a much higher output. The car has never had a problem until I recently had someone else change the oil (I have always changed it myself but got lazy), they put in a new, but not quite correct, drain plug and it leaked oil all under the car. Oil now seems to be all over (an exaggeration as the engine is actually quite clean except for the underside now). Suddenly I have this problem. Any thoughts? Thanks for your advice.