This spooked me, too, the first time I drove my E320. It is normal for the oil gauge to be "pegged" while driving, and low and fluctuating a bit while at idle (especially when in gear, at a light, in hot weather). This, though brings up a question. Why did MB design a gauge like that. It seems to me that it is just as valuable to know that your oil pressure is too high as that it is too low. If the "normal" position while driving is pegged, how does a person see if something is blocked?