Your best bet is to remove the contaminated soil and replace it, as Snoopdog advises. It will take a lifetime to recover on its own. (The professional oil spill companies can treat the soil with a bacteria that will eat the oil but this is very expensive) I should advise you to take the contaminated soil to a special waste disposal site, but do you have a section of path that you could dig out and replace the good soil with this contaminated soil?

depends how long its been there the scrap yard near us when it closed down they had to remove 2 feet of soil.good luck.

As others have said, the only way is to remove the contaminated soil. If you don't, it will take a very very long time to get rid of it completely. Treating the contamination with manure and compost will only dilute it. The oil will still be in the soil and it is probably one of the worst things that you would want in a soil that plants are growing in.

Plants that are grown in soil that contains even small amounts of engine oil will not do well. The oil that is absorbed through their roots will cause problems.

If you are thinking of growing vegetables in oil contaminated soil, then I would think again. Engine oil, which is a petrochemical, is poisonous (carcinogenic) if ingested. The oil would be absorbed through the main plant into the vegetable that would be eaten.