I would 100% avoid coconut oil or any organic oil for wood. It can go rancid and ruin your tools.

You can buy food grade mineral oil from your local pharmacy. Just rub some on with a cloth, and keep applying as long as the wood will soak it.

Reapply when the wood lightens.

Source: I make cutting boards and such as a hobby.

I archived the link for later referall: http://archive.today/2025.02.17-101747/https://www.eater.com/24204468/how-to-preserve-wooden-cooking-tools-spoons-cutting-boards

A little extra TLC can turn your wooden cutting board into a family heirloom

The reason I have a cutting board in the first place is because it is expendable and, unlike, say, a table or countertop, it doesn’t matter if a knife cuts into it and damages it. Like, it’s literally the expendable surface between the knife and the thing I don’t want to suffer wear and tear.