Hey Dave:
The greatest damage from too much
oil is due to loss of pressure caused by the
oil getting beaten into foam by the crankshaft. If you did not have a loss of
oil pressure the oil level probably did not get high enough for the crankshaft to reach it. The higher the viscosity the faster it foams.
If you have ever seen the infomercial where the gizmo turns skim milk into a delicious whipped topping then you can imagine what the oil turns into at 2000 RPM.
Bob