I typically soak the magic sponge in water and then apply some Lexol leather shampoo gel. This will help to remove all unwanted excess oils, dirt and sweat residue, and mildly conditions the leather at the same time.Magic Sponge for the steering wheel
Don't forget, if you drive your car everyday, your hands will be on the steering wheel all the time, and depending on the conditions inside the cabin, and if you do actually have sweaty and oily hands, all this will accumulate on the leather and slowly degrade the material. All leather steering wheels are not "maintenance free", unless you don't drive it at all and leave it covered inside your garage.
Also it depends on where your car is located on the globe, if you are in a place where temperature is constantly over 30C and high humidity, this will have a large impact on the leather materials inside the car.
Most car owners in general, don't pay much attention to the care of the leather inside the car, especially the steering wheel, but it is in fact the one part of the cabin (besides the driver seat), that is used constantly every time you drive the car.