Read your compressor owner manual.
Oil should be changed after break-in just like on a gas engine and because there is no filter it is more important for the first one.
Your car manual says to change the oil after so many miles or after X months, even if the car is not driven.
OIL ABSORBS MOISTURE.
Just like in a car, oil absorbs moisture from humidity and short heat cycles causes condensation.
You don't need compressor oil, just a good quality non-detergent oil.
I do try to change mine every two years, but time has a tendency to slip by.
