You do need to oil an electric motor if the electric motor has oil ports which are located on each end of the motor housing where the motor shaft exits the motor.
Some electric motors have sealed bearings and don't require any oil and if there's no oil ports or grease ports the electric motor does not need any oil or grease.
But if the electric motor does have oil ports or grease ports they need oil or grease to keep the bearings lubricated.
The kind of oil that you use in a small electric motor is often 3 in 1 motor oil or SAE 20 motor oil.
The best oil for electric motors including small electric motors is 3 in 1 motor oil or SAE 20 motor oil.
3 in 1 motor oil or 3 in 1 oil in general is best for electric motors for lubrication.
3 in 1 motor oil is the best for electric motor bearing lubrication.
SAE 20 motor oil can also work in electric motors for lubrication.
WD-40 is OK for electric motors when cleaning and freeing up any stuck components although WD-40 shouldn't be used as a lubricant for the bearings as WD-40 is not an actual lubricant but is instead mainly a cleaner and penetrating solvent.
3 in 1 motor oil is different than the regular 3 in 1 oil.
Some larger electric motors may require grease or a thicker oil depending on the size of the electric motor although most household sized electric motors can use 3 in 1 motor oil or SAE 20 motor oil.
10W 20 motor oil or other light oils can also work for small electric motors.
And for electric motors that need grease, the grease consistency preferred for electric motors is normally NLGI 2 or 3, with a base oil viscosity of 100-150 cSt @ 40°C or 104 F.