For the right grade oil see:

http://api-ep.api.org/filelibrary/Guidechart2002.pdf

Quick oil change places,(and any shop) are only as good as their
workers; those workers typically learn by doing so if your area has many
M-B cars it may be OK, if not, your car will be their learning curve.

I own the same model and take mine to an independent M-B shop and they
make mistakes - like overfilling the oil.

Rough idle is unrelated to the oil or oil level. This engine should be
tuned up every thirty thousand miles - yours is due, and expect to
change one or more of the three coils as well as the spark plugs.

Nice car.

1997 E320 purchased at 90,000 miles, the car has been running well
since the purchase 6 months ago.

Last Friday I had the oil changed by Mobile Pit Stop, an at your
office service which is extemely convenient, at 93000 miles. The oil
they used is called Oil Extreme and includes an additive see
http://www.oilextreme.com/.

The last oil change, according to the book, had been at 80,000 miles
with 20W50 Mobil.

On Friday the car ran quite well on my way home but on Saturday I
found the car idling a little rough and the engine sounded noisier. I
checked the oil level on Sunday morning after the car had been sitting
level for at least 10 hours and found the oil level over the max mark.
The invoice says they put in 7 quarts of oil which is less than the
recommended 7.7. The oil filter was changed with a new one which I
provided.

I'm going to take out some of the oil and bring it to the right level
but I'd like to hear opinions about non MB oil change services and
oils.

Thanks,
Anil