Head west from the starting point (where you start after the game beginning intro) and at the edge of the map you will find a fuel station. Climb on top of the fuel station and stand underneath the fossil fuel mascot (dinosaur) and he should squirt oil over you to give you this achievement. You may need to adjust your position slightly if it doesn't activate, there may also be a second fuel station but i'm unsure about that.
If you need more help with this you can see how to do it in my video below, it will start at this achievement: