Spruce generously with baking soda to soak it up. Then I guess you can finish with vinegar or something acid based.
How Do I Get Grease Stains Out Of Unfinished Wood?
Pour kitty litter over the grease to soak it up. Remove the kitty litter once most or all of the grease is gone. Wash the area lightly with warm soapy water and let it dry. Bleach can also be used to remove the stain.
I have an unfinished piece of oak that has a grease stain on it. The furniture has never been finished,still in the unfinished state. How do I remove this grease stain?