"New" 81 300SD... and having buyers remorse

[81mercturbo]

I purchased an 81 SD from my brothers neighbor for $4800.00 and I am having serious remorse. The car has 198k miles on it with a new tranny and power steering pump, along with all new window regulators.

The car is leaking really black oil, I can deal with it leaking, for now, but is it normal for diesels to have such black oil? I am afraid to drive it in fear I am going to screw up the engine. The oil level is perfect, pressure is where it should be and temp is right at 80 all the time... but from driving a Honda before, this is not normal for me to see black oil like this.

I have never changed the oil in any car before so I have an appt with my local MB shop for monday to do an oil change and general look over of the car. Should I not drive it in the mean time? Do I run the risk of destroying the engine with black oil?

The car hadn't been driven for 4 or 5 months when I bought it so it just sat. The car pre glows like it should and starts right up without issue. I am new to this whole diesel thing as an adult... 1st car was a 77 240D... I am needing some reassurance here that I did not make a BIG mistake and if I should get out now.

Is there anything I should pay close attention to while driving, other than the temp and oil pressure... any sounds to listen for or anything?

Thanks in advance!!