Is the oil leak at the top of the tube where the DIPstick goes into the tube, or at the base of the tube where the tube enters the crankcase?
The goldish look is due to a waxy preservative MB sprayed pretty much everywhere except the interior before shipping. It typically was never removed from the underhood area, just the body. Through time the waxy coating kind of bakes on there and turns a brownish-gold color (depending on how hot the individual areas of the engine got). The area under the air intake tube never got sprayed (the tube did instead) which is why under the tube is still silver.
As far as what color it's "supposed" to be, before it got sprayed with this crap it was silver, like under the intake tube.