Oil in Fuel

[Dustink1984]

The cylinder head is original head on the truck was only removed due to oil leak at back of cylinder head from the head gasket. We don't remember seeing the davco turning black prior. Yes the Fuel in the Tank is black as well, have not sent it off for a sample yet. But we have the truck running off a separate fuel source directly at the davco and davco was still turning black. Is this a normal issue then? I understand there is no way telling without a sample being done.