ISO 6743-99:2002 establishes a general system of classification, which appliies to lubricants, Industrial oils and related products, designated by the prefix letter "L".

Within class L, 18 families of products are defined, according to the application areas of each, so as to cover, as much as possible, all the applications where lubricants, industrial oils and related products are used.

The detailed classification of each family is given in other parts of ISO 6743.

The classification only applies to new products.