I was flushing my motor after a day out and it was the first time I had flushed it out on a driveway (normally done at the boat ramp). Anyway I noticed it left a bit of a stain on the driveway. Almost looked like the kind of stain you get on a sidewalk that has been sprayed with well water, but not that dark. Any ideas?<br /><br />1995 Mercruiser I/O 3.0LX 135HP