Inside the owner's manual you're getting is a guide that shows the recommended oil for your type of driving. It mostly depends on the temperature in the areas you'll be driving. In some cases you can use the same oil year round, in other cases there's different oil for the winter and summer.

The manual will not discuss the differences between synthetic and nonsynthetic oil. It's probably not the most important decision you'll make regarding your car.

Sixto
91 300SE
81 300SD