I have a nagging problem with the oil on my 1991 560SEL.

The oil light will come on after the car has been driven for a while. My mechanic has told me that the light is linked only to the oil level, but the light will come on even with the crankcase properly filled.

Last winter, on some days, I was able to get all the way to work (~20 miles) without it coming on. As the days got hotter, the light would be on right at ignition in the morning. Now that we have seen some cooler days, the light is off in the morning, but it comes on about half way to work.

There is also a slight smell of burning oil after I shut the car off, but I think this might be related to the slight leak (3-4 drops on the floor every morning).

Can anyone point me to what the problem might be?