Oil Valley
From Transformers Wiki
Oil Valley is located not far from Autobot City. It's filled with oil rigs that constantly pump oil out of the ground.
Fiction
Marvel coloring books
Low on fuel, the Decepticons began eying up Oil Valley and decided to enslave the humans there. Hot Rod and Daniel Witwicky, who were taking a joyride, happened to spot them and headed back to Autobot City with the Decepticons in pursuit. The human workers, drawn by the sound of the battle, climbed out of the valley to see what was going on, and Galvatron took the opportunity to try to grab the oil for himself. Though the other Autobots were occupied, Grimlock followed him into the valley and hit him with an oil tower until he retreated. The victorious Autobots got a rousing cheer from the human workers as they left. Battle at Oil Valley