I've always used oil on Butcherblock -- mineral oil, even olive oil, since i'm cooking/prepping food on it. The raw finish is why most people go with butcher block. Cover it with a thick coat of oil, let it soak in then wipe off. But If depends on what kind of wood your butcher block is made of. I have acacia from home depot and it's not like regular butcher block. I treated it with the this oil wax. It's a beautiful finish without hiding the wood behind polyurethane,
Interbuild 8.5 fl. oz. Espresso Hardwax Wood Oil Stain 471-3651D-025V - The Home Depot
Interbuild 8.5 fl. oz. Espresso Hardwax Wood Oil Stain 471-3651D-025V - The Home Depot