Reply to "Coolant or gasoline in oil?"

It doesn't take much coolant in engine oil for it to form an emulsion.

A head gasket leak to combustion chamber would normally show up as either a) white smoke (steam) from one bank on the exhaust as the rings should do their job in preventing that water getting into the crankcase. or b) over pressured coolant system.

A water passage to oilway leak is often very difficult to pin down as once you remove parts the evidence is often lost. Being optimistic and assuming it's not a cracked block, the two most likely places are head gasket or water pump/timing cover leak. First I'd pull the intake manifold and see if there is any evidence of coolant in the valley.

Has the car been subject to any extreme cold temperatures?

Julian