Is that last one (which I like a lot better than the first) only mud or is it mud with an oil spillage? Oil - desastrous as it can be for nature, just as the Gold Coast Australians just now - creates wonderful effects and - as_you_can_see - I have nothing against oil+water colours.
it's not even mud really, it's water on my road flowing from one puddle to another. it carries a bit of silt from the road and when it flows into the more settled water of a puddle the silty water and clear water mixed like this until the silt settles to the bottom of the puddle. im sure you've seen the effect before. and yes i've seen the oil drops i'm sitting around the house for the next week or so with nothing to do, so i may have to try a setup like that at somepoint.