The Octan Empress, a tanker carrying petroleum from the legendary Oil Asteriods of Alpha Sigma B. It also carries crew for restaffing the Oil Platforms. Octan: terraforming through greenhouse effect, one planet at a time!
Yep. Oil Asteriods of Alpha Sigma B. Imagine a world where oil producing bacteria go out of control, making entire oceans of oil for millions of years. Then an unlucky meteorite or comet impact smashes the planet to bits, and there you go: oil asteriods.
Or you could try to figure out a better reason for an oil tanker in space!