End grain cutting board drying out?

I make cutting boards for friends and family out of walnut or cherry wood. We always use vegetable oil to treat the boards and it works very well and is safe. I also treat my wooden knife handles to keep them looking new. When they get rough, simply sand them with a 150 to 180 grit sandpaper. This will keep them looking new for years. Remember to treat them before they get too dry or water can penetrate and cause them to crack. Just rub on the oil and wipe it off. And......never put them in the dishwasher.