The majority of the heat that engine oil has to shift is that due to friction within the oil and moving parts, so it's unlkikely that a thicker oil can run cooler.
The majority of that heat has to be radiated out of the sump, using the temperature differetial that exists between the sump and the atmosphere. In order to MOVE more heat, it needs a greater deltaT
The majority of that heat has to be radiated out of the sump, using the temperature differetial that exists between the sump and the atmosphere. In order to MOVE more heat, it needs a greater deltaT