welcome. yes, atleast every year, before the first freeze. this is to make sure there has been no water intrusion. if the is water in the lower unit it will freeze and expand, cracking the lower unit.
There is always some wear in a gearcase which produces tiny metal particles which over time can cause accelerated wear; changing the oil gets rid of these bits.
Changing the oil every year is much cheaper than changing the lower unit every four or five.
