Petroleum-13 (or 13Petroleum or 13P) was a synthetic molecular isotope created originally on Earth, but successful synthesized on Centuria. It was made up of the common and stable isotopes of it's constituent atoms (hydrogen and carbon). Petroleum-13 was used as a simplified and energetic surrogate for Petroleum. The standard selection of Petroleum-13 (43 g) contained nearly 6.2 gigaverms of energy. Petroleum-13 was a constituent and back fuel for Centurian starships, although they mostly utilized Filormium-313.