Car Gearbox oil and transmission fluid

Automotive transmission oils are lubricants for gearboxes, final drives / rear differentials, transfer cases and other mechanisms. They protect the parts of these units from abrasion and corrosion, minimize energy loss due to friction, withdraw heat from contacting elements and clean them, neutralize shocks and vibration, preventing their impact on gears. In modern cars, this type lubricants should withstand very high loads: pressure of up to 4,000 mPa, sliding speed of up to 25 m/s, heating of up to 300°С.

Classification of transmission oils

According to the classification of American Petroleum Institute (API) all automotive transmission oils can be divided into a few groups:

• GL-1. These are products for manual transmissions operating in rather mild conditions. They are used in some commercial vehicles and special vehicles operated in conditions of low speeds and loads. They can include inhibitors of corrosion and additives preventing foam formation.
• GL-2. They are made for vehicles operating in conditions of low speeds and loads. They are used in transmissions of tractors and agricultural machinery. They can contain insignificant amount of antiwear additives.
• GL-3. They are designated for protection of transmissions of cargo vehicles, which are operated in conditions of average loads. Their formulation includes up to 2.7% of antifriction additives. They are not suitable for hypoid gears.
• GL-4. This category includes products made for various units of passenger and commercial vehicles. They contain up to 4% of extreme pressure additives.
• GL-5. They are used in hypoid gears with large axial offset, which are operated in conditions of heavy loads. They are characterized by 10% content of multi-purpose additives. Nowadays, only products of this category can undergo API testing and get an official approval.
• MT-1. These are lubricants for units which are operating in conditions of extreme loads. They are used in non-synchronous transmissions of buses and heavy diesel cargo vehicles.

API standards are not applicable for AT transmission oils. Their standards are defined directly by transmissions manufacturers.

American Society of Automotive Engineers (SAE) offers its own classification:

• 70W. They can be used at –55°С. They have 4.1 mm2/s kinematic viscosity.
• 75W. They withstand up to -40°С temperature. Their kinematic viscosity is also 4.1 mm2/s.
• 80W. They retain the density, sufficient for operation of the transmission at -26°С temperature. At 100 °С, their viscosity is 7 mm2/s .
• 85W. They are permissible for use at the temperature of -12°С and higher. Their high-temperature viscosity is 11 mm2/s.
• 90. They are not suitable for subzero temperatures. Their kinematic viscosity varies in 13.5–24.0 mm2/s range.
• 140. They are also not used in winter. They have 24.0–41.0 mm2/s viscosity.
• 250. They are used at above-zero temperature only. Their viscosity is not less than 41.0 mm2/s.

Nowadays, car owners increasingly prefer all-season lubricants. They have double marking, which indicates both low- and high-temperature characteristics of the product.

Types of transmission oils by formulation

According to the formulation, all lubricants can be divided into:

• Mineral. They are made on the basis of paraffin and naphthene components. They are inexpensive and suitable for use in conditions of low and average loads.
• Semi-synthetic. They are made on the basis of hydrated compounds. They have advanced characteristics. They withstand high loads. They are notable for an optimal price.
• Synthetic. They are based on polyalphaolefin compounds. Such products, despite their excellent characteristics, are nowadays rarely popular: cost of synthetic-based transmission oils is rather high.

onlinecarparts.co.uk: high quality transmission oils for your car

A wide range of this category products from such well-known manufacturers as Aral, Dynamax, Blue Print, Castrol, Febi Bilstein, Elf, Mobil, Motul, Swag, Vaico, ZF and others, is presented in our online shop. You will easily and quickly choose the most suitable lubricant for your car. Making purchases in our shop is not only convenient, but profitable also: we provide significant discounts on all the products.