I did detailing shortly as well. That is too high of a ratio for degreaser. It can damage the leather easily. Try 1:4 at best. Also, he didn't say he wanted a cleaner, he said he wanted a conditioner. That being said, first use the formula I said (1:4 water to degreaser) and brush down the seats. You'll be amazed at how dirty they are even if it's a new car. Then, get some conditioner and throw it on there. I used Wilsons (like the coat store) conditioner. I think it works well because what it's intended to be used for has a lot of traffic (your coat). Good shine, makes the leather soft after the degreaser dries it out.i was a detailor..we used lexol.
they have a cleaner and conditioner. IMO the cleaner was garbage, 50/50 degreaser (purple power) and water with a scrub brush worked better..but the conditioner was pretty good stuff.