General information on the mission
The thirteenth mission of Metal Gear Solid V is the first one that takes place in Africa. Therefore, you should not hurry too much here, due to the unfamiliarity of the area. The key part of the mission takes place in the Northern oilfield, where you need to sabotage two installations. Of course, you will be prevented by your enemies and, additionally, towards the end of the mission they will also call for reinforcements (you can either fight them or leave the map). On your way to the oilfield, you can make a stop in two villages, where you can complete secondary objectives.
PRIMARY (1/2): Shut down the oil transfer pump - The mechanism that controls the pump is located inside one of the buildings on Mfinda Oilfield. After you have located it, you simply need to interact with the terminal to disable the pump.
PRIMARY (2/2): Destroyed the oily water separator tank - The tank is on Mfinda Oilfield. Since it is red in color, and it is sizeable, you will have no problems locating it. You can blow up the tank by attaching a C4 explosive to it, or by firing at it the rocket launcher, or the grenade launcher, at a distance.
SECONDARY (1/4): Extracted 4 child soldiers being trained at Bwala ya Masa) - This objective is challenging. You need to restrain four marked opponents, before they leave the map. Additionally, the kids cannot be fultoned, therefore you need to deliver them to a helicopter landing zone (you can use the jeep in the village, for that).
SECONDARY (2/4): Exfiltrated the hot zone before Mfinda Oilfield was sealed off - Reinforcements appear soon after you destroy the tank in the oilfield (the second primary objective). Before you do that, destroy the radar in the base, thanks to which you make the landing zone in the village available. Also, you can request pick-up beforehand and leave the area of mission right after the detonation.
SECONDARY (3/4): Extracted the lappet-faced vulture that wandered into the burned-down village - This village can be found within a short distance to the South-West of Mfinda Oilfield. Sneak up to the vulture, use sleeping ammo and fulton it.
SECONDARY (4/4): Extracted 4 Walker Gears sealing off Mfinda Oilfield - Walkers appear on the site soon after you have destroyed thee water tank on Mfinda Oilfield. Two of them reach the Southern entrance to the base, and two more to the Eastern one. Deal with the operators of the walkers in any way you want and fulton the machines (requires the CARGO 2 upgrade).
This time around, you will be unable to pick neither the landing zone, nor the starting time of the day. Still, if you do not like the time, you can use the Phantom Cigar to pass time. You can take along any buddy that you want, but the D-Dog will prove most helpful, while securing the oilfield.
Before you head out on the mission, it is a good idea to get the best sleeping ammo weapon available, thanks to which eliminating the juvenile fighters in the village will not be too difficult. Additionally, make sure that you have C4 explosives on you, which you are going to use to destroy the tank and the radar on the oilfield (instead of the C4 explosive, you can also use, e.g. The grenade launcher).