API/DIN CLASSIFICATION OF GEAR OILS
Gear oils are classified by the American Petroleum Institute using GL ratings:
• Gl-1 – Designed for gearboxes operating at low sliding speeds. It does not contain any EP additives and is often used in applications containing parts made of yellow metals. Additives can increase resistance to oxidation, protection from corrosion and freezing point.
• Gl-4 – Designed for gearboxes and main hypoid gears operating at high rotation speeds and low torques.
• Gl-5 – Designed for gearboxes and main hypoid gears operating at high rotation speeds with impact loads and low torque or at low speeds and high torque.??
Gear oils are generally classified in Europe using the DIN 51517 standard. The following DIN 51517 classifications of gear oils are used most often:
• Din 51517 CGLP – Contains additives that protect from corrosion, oxidation and wear at the mixed friction spots, as well as additives which improve characteristics of sliding surfaces.?
• Din 51517-3 CLP – Contains additives which protect from corrosion, oxidation and wear in the mixed friction zone (this is the Siemens MD specification).?
• Din 51517-2 CL – Contains additives that protect from corrosion and oxidation, suitable for average load conditions.