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I made a comment earlier which implied that you will not be able to drive on your national license as a visitor in Oman. My comment was based on this statement on the IDP website
All visitors who plan to drive in Oman must make sure they obtain an IDP in their home country or country of residence before they travel.
However, after some research it appears like the answer is No you don't need an IDP; You can drive using your National License if you are a visitor. If you receive a residence permit then you will have to apply for a local driving license in Oman.
ExpatArrivals states that
Expats can drive in Oman with their national driver's licence if on a visitor visa. Anyone applying for a residence visa for Oman may also drive with their national driver's licence. However, once the residence visa is issued expats need an Omani driver's licence.
(The emphasis is mine)
JustLanded states that:
While on a visitors visa, expats are allowed to drive with their own national driverβs licence. Once a residence visa is issued, expats have to obtain an Omani driverβs licence
WikiProcedure states
NOTE: A foreign tourist can use his own country's driving licence or an international driving license for 3 months.
AutoDriverClub states that
A short-term visitor in possession of a valid driver license and presence of International driving permit may drive in Oman, but any Oman resident must have an Omani driver license.
Lastly, one extremely reliable source, GOV.UK, informs British public that
If you are a visitor you can drive a rental car using your UK driving licence (both parts must be shown). If you are applying for residence in Oman you can also drive on a UK driving licence until your residency permit is issued. After that, you will need to apply for an Omani driving licence within 6 weeks of receiving your residence card. Residents may find that a UK driving licence is not deemed valid for insurance purposes if an accident occurs.
Although you have clearly mentioned Germany as your nationality but since I can't find an official German reference I don't see any reason why Germany would be an exception to this practice.
Hence it can be safely said that as a tourist Yes You Can drive in Oman legally using your German License. Nowhere do I see any requirement of Translation either.