Sonic the Hedgehog: Robotnik's Oil is a children's picture book published in 1994 by the UK publishing company Ladybird. Like its companion book Sonic the Hedgehog: The Invisible Robotnik, this book features a center page that folds out. The setting of this story is the Aquatic Ruin Zone (referred to as Aquatic Ruins Zone in the book).
Robotnic has discovered oil in the aquatic zone of the planet Mobius and has plans to construct a giant oil rig to extract it. But our superhero Sonic is determined to save his planet from the menace of pollution by sabotaging the evil villain's poisonous plans.
The book opens as Sonic the Hedgehog is running through Aquatic Ruins Zone doing the usual: defeating badniks and collecting rings. He comes upon a mass of oil-drilling machines and Doctor Robotnik, who proceeds to run at the hedgehog. Sonic, however, simply runs around him so quickly the doctor gets dizzy and falls over. Sonic tells Robotnik he will spin him again if he does not tell him about his new scheme.
The doctor quickly comes to his senses and reveals that Aquatic Ruins is above an oil field. Concerned with the state Robotnik will leave the environment due to his oil mining, Sonic speaks to Robotnik about it, to which the latter says he does not care. Sonic says that he cares, and goes off to stop him. Of course, Robotnik attempts an escape in his Egg Mobile, but, becoming unaware of where Sonic is, he crashes into a stone pillar due to not paying attention to where he is flying. Upon this, Robotnik commands his Grounders to attack Sonic; the hedgehog simply destroys them with his Spin Attack. After defeating the Grounders, Sonic runs into a group of Whisps, whom he easily takes out by dodging them at the last second.
At this point, he has found the equipment Robotnik is using to extract the oil and begins to make modifications to each piece as he passes by them. Later, Robotnik returned to see his drills still functioning. Soon, the ground began to shake, making Robotnik think he had struck an oil well, but to his dismay, he became soaked with water instead.
However, Robotnik did not know Sonic had caused that, and, coming down with a cold, carries away all the pieces of his machinery and flies away in his Egg Mobile. The animal friends appear with Sonic to congratulate him on his new victory, to which Sonic credits due to Robotnik not possessing super speed, superheroism, and not having the overall quality of a hedgehog before running off.
A cassette tape narrated by Rupert Degas was included with some of the books.
Tails makes a non-speaking appearance on pages 2, 17, and 34 (17-18 fold out). Oddly, Tails is never mentioned directly by Sonic or Robotnik.