Thanks... well everytime I look at it when I get home and raise the hood, the level is always at the seam. As mentioned, I added some, but I have not driven the car since. I only drive this car a couple of times per week. I do not think its leaking, because there are no drips at all of anything under the car. I have also noticed that at some point the radiator has been replaced and its not leaking either. I know these engines have reputations for head-gasket issues, but I think when they fail, its different than when other cars tend to leak. When I think of headgasket issues, issues I see on most cars is oil in the coolant, coolant in the oil, overheating, steam out of the exhaust, etc, but on these cars, I have never heard of that being the problem when the HG fails. It seems on these that they either leak coolant at the head or they burn coolant, etc, but I would think it would steam then out of the exhaust all of the time. My car has nearly 155K, so I am hoping its already been replaced. My car does not overheat at all either. It normally always runs at 80°c or slight above or below. No coolant smell from the exhaust, no oil in coolant, no coolant in oil, etc. Also I do not think the coolant level is going down, because as mentioned, it stays at that seam area, or just slightly below.

I am just hoping its not a leaking heater core or something. I do not see any coolant under the hood leaking or and coming in the cars floor, but I am not sure where the coolant leaks on these when the heater core is bad.

As mentioned, the level is not really going down, but the light comes on sometimes when pulling out, but later even on a steep grade, it dont come on. Maybe like someone else said, it could be a faulty coolant level switch. I have a 1991 Lexus LS400 and the coolant level sensors have been known to fail on these cars. My car is no exception. My low coolant light (its a little yellow light on the lower left instrument cluster that looks like the Washington Monument, that is supposed to be a radiator ) that is always on, despite the coolant being full and always being full. The new sensor is $81 from Lexus, so I will probably replace it soon.

I will just drive the Benz and watch the level again. I am not sure if the coolant level always stays at that 1/2 way mark even when the radiator itself is low... does it?