I recently purchase a boat with twin 1999 350 Mer cruiser magnums-the boat and engines were neglected. The issue i am having is the port engine which runs ok continues to have dirty blacken oil, even after 5 oil and filter changes. I assumed at some point the oil would appear cleaner- with similar hours on the starboard engine the oil appeared clean after one change. The engine in question does burn a bit of smoke and smells gas rich as well. The mechanic I hired states compression was good all around. Any theories are appreciated.
