From snopes:
As for the claim the "basic ingredient" in WD-40 is "fish oil," it's a common rumor and one that is easily propagated (because cans of WD-40 spray include no ingredients list), but a glance at the composition information included in the Material Safety Data Sheet (
MSDS) for WD-40 aerosol indicates the product is primarily petroleum-based, with the main ingredient being "
solvent naptha, petroleum, medium aliphatic" (also known as
Stoddard Solvent):
- solvent naphtha petroleum, medium aliphatic, > 60%
- petroleum base oil as paraffinic distillate, heavy, solvent-dewaxed (severe), 15% to 25%
- corrosion inhibitor unregulated, 1% to 10%
- wetting agent unregulated, 1% to 10%
- fragrance unregulated, 0% to 1%
- carbon dioxide, 2% to 3%