Not sure what you mean by a leather "sealant" but I assume you are referring to a protectant. Most of today's cars have treated leather. That is, the seats are coated with a vinyl-like protectant, unlike natural leather. Some Euros and perhaps a few high end American cars might still have natural leather but most do not. As such, no further protectant need be applied. However, to resist cracking and enhance appearance, you could try Protectant 303. Unlike leather conditioners, Protectant 303 provides UV protection (here in Texas that is very important). It is an aerospace product and gives as good a UV protection as you can find anywhere - and it is approved for leather as well as rubber and vinyl. It can be found at boat, motorcycle and hot tub dealers as well as on line, even at Amazon.com. Great stuff!
