First of all, there's actually 2 oil rigs on any map: Big and Small oil, or Smoil for short. The latter needs both a blue and red card, while the former only needs a red card. Some might be intimidated by these monuments, but they are pretty easy, as long as you're careful and aware of your surroundings. Take plenty of ammo, heals and a friend or two, and find a ride. If you can afford it, a helicopter is the best and fastest way to get to the rigs, but a boat is a tried and tested and, more importantly, cheap way to get there. A locked crate can be found at the top of the Rig, providing some of the best loot in the game.