What is "oil stain"

Usage examples of "oil stain".

And there was an oil stain on the concrete, about ten feet to the left of the Caddie, which told him that Ambler had two cars.

She glared at the big black oil stain on the driveway where the truck had been parked.

There was a large oil stain on the ground, and the lube points were practically covered by caked-on dirt.

Kelly was just an object to him, one of the things that occupied the street, of no more interest than an oil stain on the blacktop.

It grew rapidly, amoeba-like, its black, widening center an oil stain spreading across the air.