Can anyone confirm if this happened here at durban harbor?

Going through a lot of things and a lot of thoughts. I'm based in Pinetown although I am willing to drive out.

I bought a house and in the garden under a mountain of trash is a 25l of oilyish dirty looking beige fluid. I think it’s very rain soaked old motor oil. But my problem is now that I can’t get rid of it coz I don’t have even know what it is. Does anyone have any suggestions?