If you need to clean the seats first, I use either the Pelle leather cleaner ,available at large supermarkets or leather stores or as Lexus reccomends a mix of 1 part Softly or other liquid delicate laundry detergent to 6 parts water
Remember you must put a conditioner on after this as all the cleaning products strip the oils and as said before while you can use any leather cleaner ,the conditioner has to be car specific to deal with the UV