Spagyri-Zyme Probiotic Enzyme is the name of that product that Phoenix referenced. Spagyri-Zyme completely eats through the paraffin layer of both crude and synthetic oils. Place the Spagyri-Zyme on the affected areas and then till the soil in. If you are trying to clean the soil of toxins, chemicals or car oil, we would also suggest using Aquazyme and Oppenheimer Formula 4OR a more intense Oppenheimer Formula if you have a REALLY bad situation [like an oil tanker spill]. After that, you will want to get various types of compost [wood chips, lactating dairy cattle manure, leaf mould, etc], aggregates like Coco Coir and Peat Moss, and a bunch of amendments [azomite, basalt, gypsum, crab/oyster/lobster shell, Cal Phos, etc] and till all of that in and then inoculate it with Stubble Digester in the fall and let it overwinter. As soon as the ground thaws in spring, then you will need to prepare the soil for planting by creating compost tea preparations with a variety of Microbes [including EM-1, Spagyri-Zyme, Jadam-style plant ferments, and those from Earthworm Castings] or use an instant compost tea product like Organic Plant Magic. And then you will be ready to plant and you will probably have the best soil of any place around. Then, you just have to continually perform top dressing or live mulching and compost tea preps and your soil will continue to stay amazing.