I recently applied the following to 100% of the leather surfaces in the truck:
1. Chemical Guys Leather Cleaner, cleaned with horsehair brush
2. Chemical Guys Leather Conditioner. Applied and then let sit overnight. Came back the next day and hit the spots that I missed or looked like they could use another application.
3. Chemical Guys Leather Protectant Serum. I used a thin coat of this as I didn't want to mess with the excellent smell and feel left by step #2. After applying and let it penetrate for a few minutes, I wiped dry with the same rag I used for step 1, but I applied no additional cleaner. This seemed to give the leather a clean feel again, and it maintained the luster gained from the conditioner.
So it turns out that my brand new truck's leather interior was in rough shape. I bought it new as a 2019 two months ago, so I'm guessing it has sat for 9+ months on the dealer's lot, just soaking up sun and never getting cleaned (it only had 100 miles on it when I purchased). So the leather was dry. Very dry. It would soak up almost an oils from my fingertips. That's why I mentioned a sweat stain on the headrest. Any moisture and the leather soaked it up. Well the Chemical Guys products restored it to what it should be. Now the leather has a deep, soft sheen. It feels soft and smells great. Now when I get in my butt actually slides across the leather seat like it should. Previously, I could feel a lot of friction when scooting into place. I'm thrilled with these Chemical Guys products.