There is a new update regarding the parking at the Muscat Intl.Airport.
The Airport has a new long term car park which is situated beside the Cargo building. Its called Car Park 4 and you can access it directly from the highway if you turn off at Cargo OR driving past Car Park 2 if you are inside the Airport Perimeter.
It sounds a bit unclear to me but the new rates are as follows:
1-2 days 2 OMR/day
3rd day 3 OMR
4th day 4 OMR
5th day 5 OMR
The car park II(short-term) rates are the same:
0.500 OMR 30 mins