Old dry holster and belt leather:
Neatsfoot oil
made from hooves, is an excellent moisturizer and preservative. Knew a blacksmith who shoed working horses and forged tools and wagon hardware. Loggers brought harness to him, which he lowered by hoist into a vat of neatsfoot oil. This was done once a year. Neatsfoot oil may be applied heavy to a wide gunbelt, where flexibility is an attribute to comfort and spinal health while packing a 3-pound revolver all day, especially in the mountains.
Three drawbacks of neatsfoot oil
* Due to its ability to soften, neatsfoot oil should only be applied sparingly to a water molded holster.
* Attracts mildew in hot humid climates.
* Darkens light colored leather, which may not be desired.
Pecards Leather Treatment
Probably petroleum based, non-animal dressing, viscous like Sno-Seal, is good stuff and doesn't soften water molded holsters.
Mineral oil
As it resists mildew, mineral oil is used among some saddlery people, especially in the South.
I have never put gun oil on leather and would think it injurious. Among oil that the unknowing might try on leather, linseed oil would be the worst, as it will harden and crack the leather. Learned that as a kid, when a neighbor tried it on a Civil War cartridge box.
I try to take respectful care of my leather from the time Chic Gaylord gave me pointers on water molding my first holster for an old model Blackhawk 6-1/2" .357. Mind you, only properly selected hide properly tanned makes a long lasting holster. Over-brined leather cannot be saved. Fine skins properly tanned separate the best holsters from a great many mass produced products. Red Chinese holsters are an example of garbage-tanned inferior leather, barely a step above cardboard.
Other products listed in the thread, which I haven't tried, may be fine. If the leather is dirty at all, wipe with a damp cloth or saddle soaped. Mildew should be wiped, preferably washed and hung in the sun for ultra violet light to kill mildew. Rub in leather treatment and return to sun for several hours.
David Bradshaw