I drive a 1989 560SEL, which should be the same, as far as this problem goes. I have no whining noise, so it is not normal, (but you knew that!). Check the belt tension, maybe? A loose belt will make it whine.
I had various leaks and drips from the front of the car also. I cleaned my engine and undercarriage at the self serve car wash, then drove home and crawled around underneath. A clean undercarriage will make it easier to find the location of the leak.
Are you sure it is oil? I suggest you look at: The discharge hose from the suspension pump under the power steering pump, as it makes its way behind the water pump and around the passenger side of the engine. Also, look at the P/S hoses, (I hope the answer is "they are new", as the pump was just replaced and the labor is not much more to replace them in the process.) The transmission cooler lines run up there to the radiator too. Maybe there?
Do any of your fluids go low as you drive? This may help you track this down.
I am a fanatic about leaks too, and I found you really need to be diligent about finding them. The dealership may not care as much as you do about this. Try to find a GOOD independant shop to work with. Good luck!
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)