Board Thread:Dragon City Questions and Answers/@comment-9584828-20130515135653/@comment-4616966-20130515144322

For Petroleum, you can try one from the options above..!!

You can start with Mud + Hedgehog.. my petroleum breeds from the first options above.. btw every dragons which are contains with dark and water elements has chance to breed petroleum.. so if you ask for "most accurate".. well i just can say its just depend on your luck, like what i said before. ;)