Picard's seems to be good stuff. I've use both the regular Picard Leather Dressing and the Picard Antique Leather Dressing for a number of years. I use the former on newer items and the latter on older things that might be a bit more frail. Neither has caused any permanent discoloration that I can see (or any other problem for that matter). I once bought an old 1907 leather sling that a previous owner had treated with lanolin. Totally ruined the sling from a usability standpoint -VERY prone to stretching.
"They've took the fun out of running the race. You never see a campfire anywhere. There's never any time for visiting." - Joe Redington Sr., 1997