There is no compulsion as such that you must switch the generator oil between summer and winter unless you experience extreme temperatures. While the concept in itself is not wrong, you can simply avoid the hassle if you opt for a generator oil that can work under different temperature conditions. There are many generator oils on the market that can adapt to a wide range of temperatures. However, you can also buy an oil that caters to extreme temperatures. Very cold temperatures are ideal for lower-viscosity oils, and very hot temperatures are perfect for higher-viscosity oils.