Is there really a difference in oil for air cooled and water cooled engines?

Question

Is there really a difference in oil for air cooled and water cooled engines?

Answer 1

Air cooled engines tend to run hotter than water cooled engines, so a higher viscosity oil is used.  My airplane uses 50 weight.

Answer 2

Yes,air cooled engines fluctuates in temperature, that depends on the outside air temp. Water cooled engines are subjected to coolant temp values,let say 175 - 200degrees Fahrenheit. Selection of oil viscousity depends on engine performance ie..high compression engine, and weather temperatures.