Kroil is an industrial-strength penetrating oil made by Kano Laboratories. According to the company, Kroil loosens frozen metal parts by penetrating into spaces as small as one-millionth of an inch. The product dissolves rust without crystallising, and lubricates and cleans.
Kroil is not as readily available as other solvents. The primary way to order Kroil is directly from the manufacturer at Kanolabs.com. The product is available in a variety of sizes and packages, including aerosol cans, gallon cans and drums.
Kroil is also available at retail stores. Midway USA is an online store for shooting products that sells Kroil in 227gr. and gallon sizes. Brownells is another large online gun supply store that carries a variety of Kroil products, including aerosol spray and bore compound. Kroil is sometimes sold at Cabela's and some auto supply stores, but on a limited basis.
Although Kroil is sold through gun supply houses, it is also used extensively in manufacturing and auto repair facilities. It is popular with mechanics, who report that it works well when freeing frozen bolts and pistons.