GEAR OIL LUBRICANTS EP90/GL-1/GL-4/GL-5 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 oregano sulfur compounds. Some modern automatic trans axles do not use heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic […]