Now, for what oil to use:

You can use whatever oil you want, as long as it meets either the MB 229.3 or 229.5 standards. These standards come in either 0W-40 or 5W-40 weights.

Lots of oil companies out there that make oils that meet these standards.

Mobil
Kendall
Pennzoil
Valvoline
Quakerstate
Castrol
Shell

Those are just a few companies that make oils that meet the standards.
Some people are going to tell you that you should only ever use Brand X.
Just use whatever you want, that meets your own actual tastes, and is within your budget.

BC.