So i know its not a car, but its almost a car motor right? Anyways, i got this boat and the previous owner said it overheated really bad, then once it cooled down he could not get it to start again. First guess was head gasket or cracked head? About 10 minutes into it i found a greyish milky color oil on top of the cylinder heads, but not in the oil pan. The majority or the milky grey oil was right around the studs on the head for the rocker arms.. Is there any obvious thing that would be wrong with this that i'm not seeing? I've seen cars where they had full oil pans of just milky grey oil, but this one just has a slight build up around the rocker studs. The other thing i noticed is the pushrods had a slight amount of rust/grey buildup at the top 1/2" of them. I was thinking maybe the valve covers leaked and water got in there or something but they look like they sealed well. Anyone have any ideas if this is something weird or just a simple head gasket change?