Over time, a vehicle's leather seats will dry out and won't be soft. This often occurs from mistreating the leather, such as soaking it with water or never cleaning or conditioning it. However, over-conditioning the leather can also increase the drying speed for some vehicle leathers. You should condition seat leather no more than twice a year. Softening seat leather takes a few hours to complete.
Vacuum the leather seats to remove any dust and dirt particles from the surface. Wipe the leather seats down with a soft, damp cloth to remove surface dirt and oil.
Apply a small amount of facial soap to a damp cloth. Work the soap over the leather seats to remove ground-in dirt or oil. Buff each section with the soap until the cloth comes away clean. Wipe the area down with a damp cloth to remove soap residue.
Place the car in a sunny location. Roll down the windows. Allow the car to sit in the sun for one or two hours to warm the seats. Leather absorbs conditioner easier when warm.
Pour about a dime-sized amount of leather conditioner onto a soft cloth. Rub the surface of the leather with the cloth using circular motions. Cover half the seats at one time with the leather conditioner. Add additional conditioner to the seats when necessary. After buffing for about a minute per area, the leather seats should look slightly damp, but not sopping wet. Allow the conditioner to soak into the leather for 15 minutes.
Buff the conditioned leather with a clean, soft cloth. Buff each area for about 10 seconds. Continue to use a circular motion to buff the area. Imagine that you are buffing the wax of a car to shine the surface of the paint. Repeat the process for the other half of the vehicle.