I recently spilled some cooking oil on our new composite deck. After cleaning it twice with dish soap, the stain was untouched. As luck would have it, I ended up out of town for several weeks and was afraid the stain had permanently been set in. After doing some research on the internet, I found a suggestion to use this product.
To my amazement, after spraying Oil Eater Cleaner Degreaser on the stain and lightly brushing, the stain was gone. I'm not sure how well it works on other types of stains, but this alone saved me from replacing several expensive composite boards.