I have been trying to grow various plants in an area of my garden for 3 years with no success (honeysuckle, roses mainly). I have just been told that previous occupants (about 7 years ago) used the area to fix motor bikes and there was always oil/petrol on the ground. The people who lived here before me had the same problem. Is there anything I can add to the soil or should I just give up and pave the area?
Help With Soil
If the area is one where it would be convenient to have a paved patio, you could go that way, and use containers for your plantings. Or you could try to refurbish the soil. You would need to dig out the old soil and truck in new. I don't know exactly how deep you should dig, but you could get that information from an environmental geologist, maybe at a nearby university. Then you could embark on a program of rebuilding the soil with lots (and year) of organic matter, compost, and so on. Here are a couple of articles that have some ideas: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/lasagna-gardening.htm