I and a lot of others think the best product is pure Neatsfoot oil, not neatsfoot compound as it has man made oils or mineral oil in it. Pure neatsfoot comes from the cow so it figures that putting it back into the leather is a good thing.
Kings Saddlery has a museum full of old saddle and I read that all they will use is Skidmore's Leather Cream. It is real good and really soaks deep into old dry leather. I've heard good things about Ray Holes Saddle Butter also. Never have tried it tho' , but I use Skidmores on leather that is a little more raggy as it won't make the leather raggier. Neatsfoot is relatively inexpensive and easy to put on. It's what I put on new saddles an even a light coating will help water proof and keep the leather softer. Sun light is hard on any skin and that is what leather is.
Where are you storing it, as too much sunlight and to much wet and humid can be real hard on leather.
When it comes right down to it, about any oil is better than no oil, but some will help to rot the leather away.
Is this a useable saddle? Can you keep it in the house or a controlled temperture and moisture, building of some sort?
When you go to oil leather, it is best to dampen it with water first and let it almost dry back out a little as this opens the pores in the leather and it will take the oil better.
Hope this helps.
Good luck.
