Car leather polish is actually a misnomer. That is, there is not really a product that polishes leather. In the world of leather maintenance, there are cleaners and conditioners, and that is all. However, because these types of products restore the natural beauty and glow of the finished leather product, they are often referred to as polishes. Conditioners are usually in a viscous liquid form, and are applied using a cloth. They should never be applied in direct sun light, and should never be allowed to dry onto the leather. However, they will become more “runny” when used under hot weather conditions.
For more info, see A Guide to Car Leather Cleaning