This subject has been beaten to death on this forum over the years BUT with the unexpected interest in the King Ranch Options there are constantly more and more people visiting the site for advice on leathercare and treatment.

I have often recommended Connolly hide food, but unfortunately a couple of years ago the company ceased trading after more than 125 years.

Yesterday I went to the Annual Rolls Royce Rally here in the UK and spent some time talking to some people who are now offering what amounts to the same product.
It is apparently available in the US but more useful might be the website.

http://www.leathercaredirect.com/

Skip the intro and go to "History", and there you will find that here we actually call treating the leather "Connollising".
You will find much useful information even if you use different actual products.