Had Brake Fluid Residue on my Hands, All Hope Was Lost for my Steering Wheel Till...
This is just a little information for anyone who might find themselves in this situation. I did a caliper swap a week and a half ago, and realized the day after that my leather steering wheel was being eaten at because I didn't wash my hands well enough. The finish was flat, holding no moisture in the leather.
I tried applying leather conditioner on a microfiber towel at first, bad move, all that did was start rubbing the black dye off. Instead, over the course of that week I continuously put the conditioner on with just the palm of my hand: on my way to work, getting to work, sometimes on lunch break, pretty much any time I was around my car until gradually it blended in like nothing had ever happened. I didn't fork over money for the high dollar stuff either, just some 6 dollar stuff in a spray bottle from O'Reileys.
So if you find yourself in that situation, don't panic, just take care of it ASAP and it should be fine. Or, you know, just wash your hands really really well with some de-greaser after handing brake fluid and avoid the problem. Cheers.