Saddle soap to strip out oils - I've used the RW conditioner which darkened, but wasn't too bad. What killed any color in my boots was the RW store who used straight
How to Use Saddle Soap to Clean Your Boots - stridewise.com
STOP Ruining Your Boots With Saddle Soap | How to Clean and Condition Leather Boots The Right Way! - YouTube
How to Use SADDLE SOAP on Boots | CLEANING Leather Boots - YouTube