With all due respect to lexol as a fine product, it can be beaten. I am using Leatherique's kit to rejuvenate and recolor my seats. The top of the rear seat had been baked by the sun to a cardboard-like consistency. The Leatherique oil has softened the leather considerably. It is recommended by ther Rolls Royce Club as simply the best.
It isn't cheap, but, if your seats are very dry, it may be the only thing that will save them. If your seats have not been seriously neglected, you may be able to use Lexol.