Im not to good with the "not changing the leather color" because I usually don't care if it tints it a bit but if it squeeks use baby powder in all the nooks and crannys. I just bought a new saddle and that's worked in the past and it worked great on this one too!
Everything will darken the leather to some degree, even the sun. For light colored show saddle, they recommend you do not oil or condition them, dust them off with a soft cloth and vacuum the leather tooling.
Absorbine had a conditioner that claimed it would not darken the leather (it did, but way less than other products). I used it on my very light leather show saddle stirrups, the foot pad part, seemed to work fine, with just a bit of darkening. This is the stuff Absorbine Horseman's One Step Leather Cleaner and Conditioner