Leatherique is my treatment of choice now!
I have used many leather treatments over the years, including; Lexol, Griot's and even a product called Bick's #4 found at tack and bridle shops around town. While they all are fine products, leatherique is the only one I have found that actually softens hard leather. We all know that leather is a natural product and variations in its thickness and grain are common. The front passenger seat in my Ody seemed to be quite a bit more stiff than the other seats so I tried Griot's products. Yes, they did make the van smell sorta like a chamois, but did not soften the seat.
So I turned to the Mercedes Club site and found that leatherique was the cure for my seat. Patience is key with this product, you have to apply, let bake and then reapply. It does not take much product, just patience. After a week or so, all seats are equally soft. If you would like more info on this fine product see:
http://www.leatherique.com/
By the way, the silicone-based products (ArmorAll, EagleOne, etc.) do nothing more than clog the pores of the leather with silicone, making the surface of the leather feel smooth and not providing moisture to the full grain. I have a buddy with a Ford P/U who has been bragging about the "leather cream" they put on his seats at the car wash. His seats are now smooth and cracked!
