One can use leather conditioners on any kind of leather, old or new. However, it is safe for new cars to go for leather conditioners, which have a lightweight consistency and don't leave any sticky or greasy feeling. If stickiness prevails, your clothes may stick to the automobile seats and can damage the leather permanently. The best leather conditioner for cars and other automobiles is the one that gives a waterproof finish and protects the leather from the harmful ultraviolet rays of the sun. After all, prevention is better than cure! You also need to make sure that the leather conditioner has a neutral pH.