Diesel

The Tenth Doctor compared a TARDIS drawing power from a different universe to it's own to putting petrol in a diesel engine. (TV: Rise of the Cybermen) He later claimed that the crystal nucleus was better than diesel as he applied it to the 200. (TV: Planet of the Dead)

According to Rose Tyler, the Doctor's familiar scent was a mixture of graphite, lime and diesel. (PROSE: The Turning of the Tide)