BMW 525i -- May 8th, 2005

I'm an idiot. I pushed the car out into the driveway to hose down the engine compartment and clear off the road muck, dust, and general filth. Turns out there was a lot, and I mean a lot of oil in various grooves and valleys, and the water floated the oil up and out. Unfortunately, my driveway is contoured like a shallow bowl, so the fluid pooled rather than running off. Once the water evaporated, the oil floating on it sunk into the tarmac in the greasy, swirly dark patterns shown below.

I've subsequently dumped a load of fireplace ashes on the oily spots, and they've successfully soaked up all the oil. It's still slightly stained, but slowly fading to normal. It's not like the driveway wasn't already pretty stained to begin with.