After a few decades, it is very likely that your car's steering gear box seals will eventually fail. This isn't because of any inherent problem with their construction, but rather the seals' response to the effects of age and constant use. Since the gear box is a mechanical component with several moving shafts, ball bearings, and gears, it requires lubrication and a set of seals to contain the lubricant within the device. You will know it's time to replace them when your steering response feels loose and delayed. You will also notice some clunks and squeaks when cornering or turning as well. And the most obvious symptom of steering gear box seal failure is, of course, a leak of oil near the top where the steering shaft enters or at the bottom where the pitman shaft exits. If you want to keep your car on the road, then it is important to maintain all the systems that support the vehicle's function. And a function like steering is absolutely crucial. Without it, you could lose control of your car, damage property, and potentially hurt other people or yourself.
Gear-assisted steering is nothing new. In fact, even before we had true power steering, there were still steering gear boxes at the base of our steering column that would efficiently transfer energy from the driver's movement of the steering wheel to the movement of the car's front wheel assemblies. Without the steering gear, moving the front wheels was very difficult. Thankfully, the gearbox does a lot of work for us. But we have to keep the gears, shafts, and ball bearings that make this possible properly lubricated with gear oil. If the steering gear box seals that keep that oil inside the gear box tear or split, then the gears would cease to perform as they should. There are usually about a half-dozen steering gear seals on the steering shaft worm gear, the sector shaft cover, and where the upper and lower chambers of the box come together.
Replacing all of your steering gear box seals will take a couple of hours from start to finish.