Cleaner for aniline leather?

Hello everyone, my first post here. I have two Stickley Morris chairs covered in "grade 3 aniline" leather. They are 14 years old. At the time of purchase I was provided a sheet of care instructions that said to dust the leather regularly and never use soap on it. It was also suggested to use lukewarm distilled water and a soft white cloth and gently massage, for any stains.

My husband sometimes sits in these chairs when he's sweaty, and even though I've rotated them to try and keep him from sitting in the same one all the time, one has started to develop a dark area on the seat back, from his sweat/ body oil. What can I do for this? I've seen advertisements for companies that clean leather furniture, but not sure if this is appropriate for aniline leather and am afraid of it being ruined.

Start here:

http://www.myfurnitureforum.com/show...for-all-brands

Stains on Anilines do not come out in most cases, an ounce of prevention is worth a pound of cure.