Lexol is an excellent preservative, one of the best. Natural products like lanolin are safe and very effective. Personally, I avoid anything that is man-made like the plauge - any kind of petroleum product or distillate, silicones, etc. I am probably one of few you will find who has really soaked bees wax into leather. I did this in connection with a living history hobby for 18th c. military - the cartridge box flaps were soaked in a mix that was largely bees wax. The result is a little hard to describe. It is totally waterproof and non-breathable (bad for boots!). It doesn't really harden the leather, but it does kind of firm it up. It requires heat to soak in, but if you ever do this, first preference is just sunlight on a hot summer afternoon. Failing that, a hair dryer but KEEP ONE HAND WORKING THE WAX INTO THE LEATHER WHILE YOU DO THIS. Why? Because if your hand starts to feel uncomfortably hot, you can bet the leather is feeling the same - not good.