<P> Gear oil is a lubricant made specifically for transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery . It is of a high viscosity and usually contains organosulfur compounds . Some modern automatic transaxles (integrated transmission and differential) do not use a heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic transmission . Gear oils account for about 20% of the lubricant market . </P> <P> Most lubricants for manual gearboxes and differentials contain extreme pressure (EP) additives and antiwear additives to cope with the sliding action of hypoid bevel gears . Typical additives include dithiocarbamate derivatives and sulfur - treated organic compounds ("sulfurized hydrocarbons"). </P>

Which of the following organizations classifies the service grade of a gear lube