Originally Posted by cyccommute

Where do people come up with the stuff? Citric acid will do not a thing to grease and oil. Any compound that is as soluble in water as citric acid is will not dissolve nonpolar compounds. If you look at the link, under “Properties/Solubility”, you’ll see that citric acid is insoluble in benzene and toluene. I wouldn’t be going too far out on a limb to say that it is insoluble in just about any oil derived from petroleum you might want to pick. Citric acid is a good chelating agent which is another indicator that it is a poor degreaser. Anything that reacts with metal ions does poorly with nonpolar materials.

The reason it works so well at descaling your kettle is because it is an acid and the salts in your kettle tend to be carbonates which react quite well with acids. Think baking soda and vinegar.

Perhaps you are thinking of limonene which is in citrus peel and is used in “citrus degreasers” but it is entirely different from citric acid. As a pure compound, it would be too expensive to use to clean chains (650 mL is about $20).