I have a 1992 300SEL (W140). The oil guage works funny too. It fluctuates a lot during idle eventhough the engine's rpm is very stable. At idle, the rpm stays just a little above 500. Could this be linked to a bad oil sensor or a bad guage? I will be taking it in for repair. Someone stole my badge on the hood and the engine won't start without manually applying the throttle pedal. But once it starts it is very smooth except for the oil pressure guage.