Oil and prop.

[willy]

Thats what mine looked like, like old used motor oil with an occasional lumpyness too it. I was told it was not my lower unit oil and it does not look like lower unit oil. Check your receipts. If they changed the oil which they would of had to do when they did the seals . Lower unit oil is generally greenish, light blackish or some commercial cheap stuff is actually white and will scare the pants off of you when you first see it. My engine is a Johnson 115 and after it sits awhile after running it seeps a blackish stuff and it is definetly not the white stuff I had in the lower unit when I bought the boat or the Johnson stuff I put in afterwards (greenish). I also noticed that it will seep lightly after a change in weather, humidity and tempature.
See what the guys who know a lot more than me say here but I would bet your looking at exhaust crud seeping out.