It’s approximately 1000 km from Muscat to Salalah and this must be about halfway.
At least 2/3 of the journey is across desert and in the summer the temperatures can be upwards of 50 °C (122 °F) which takes its toll on both car & driver. Travel is best done at night in the summer months, but this has the added danger of Camels walking in the road. Sometimes there is very little if any cell phone signal, so don’t breakdown otherwise it’s a long walk. Although phone coverage is a recent worry for some people; it’s not very long ago that there was no communications at all outside the few towns that were en route. People forget that up until the late 1970’s there was no tarmac roads outside Muscat, so phone coverage was the least of travellers worries.