I totally agree with Asif's comment, don't go in April unless you really love the long drive and have only available opportunity in April.
You can add more points to your Salalah trip:
Fill up gas at every gas station as each is spread out every 200 kms stretch, even if your tank is half as you never know the next fuel station might be out of fuel - safety advise
Take 10-15 mins break every 200 kms and walk around and check / adjust your tire pressure
Carry extra fuel jerry can and lots of spare water
If you are doing it in one stretch, then sleep extra (8-10 hours) night before to counter the stress of 12-14 hours drive
Keep good music, chewing gum, candies, snacks to munch while driving as after first few hours it's very monotonous
Carry toolkit (spanner, screwdrivers, wrench, sockets etc), working jack, tow rope, and shackle.
Research and book hotel in advance because after 14 hours of fatigue, you will crash in the first or second hotel you check
@Mohd86 and @Abbas2528 please add more points based on your last visit