This is from the Oberon site. It does say you can use a light, even coat of leather lotion. Don't use oily or gooey materials on it though. Here it is below.
How to care for Oberon leather goods
Hi! I wanted to thank you for buying what we made at Oberon Design. I hope you have as much pleasure using it as we had making it. I have put together some leather care tips that can be applied to all of our leather products including our refillable leather journals and leather portfolios.
Thanks again!
Oberon products are made to last a lifetime. We use the finest, uncoated leather, tanned for us in the US. Its unsealed surface may reveal small nicks or scars. These blemishes occur naturally in all leather.
The following tips are guides only. Oberon cannot guarantee their success.
General Care:
Try to avoid leaving your leather journal or leather accessory in direct sunlight, like the dashboard of your car when it's 99 degrees in the shade. The color will fade, and along with pen marks you swore you'd never, whoops, make, these conditions are difficult to correct. Promise us you will never use paint thinner or other chemicals to remove marks or spots. They will lighten the color and make a small spot worse.
Dry or scuffed appearance:
Small scuffs can be remedied by simply rubbing them with your finger. A light, even coating of 'Leather Lotion', a product available in most shoe repair shops, can be applied. The application of any cream or oil will darken the color of leather. Never use gooey stuff like Mink Oil, Neats Foot Oil or oily dressings.
Dirt or food stains:
So you let your peanut butter and jelly sandwich drip into the surface of your leather journal. After a few weeks of pristine care it is bound to happen. Here are some tips: try removing spots with the light touch of a clean eraser. Don't go wild. For tough jobs, dampen a soft cotton cloth with plain water. Rub the spot, then the whole surface, so that the moisture is consistent. It will look mottled at first but should dry just fine.
Pewter buttons:
This tip also applies to our pewter bookmarks and hair barrettes. Like all metals, pewter may tarnish over time. The best way to bring back its original luster is to use an over the counter silver polish. Buff gently, as our pewter pieces feature very small details and may be buffed out if you are too vigorous.
How to fill your leather journal
For help on filling your leather journal without tearing the spine