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Synthetic Gear Lubricants

Car gear with a blue tint
Our high-performance gear oils protect against wear, prolong gear life and help to deliver optimum gear performance.


To increase productivity, many commercial operations rely on more frequent and prolonged high-load operation of commercial vehicles and equipment. The resulting thermal stress created in gear boxes can present challenges for the lubricant in the areas of performance, fuel economy and durability. Castrol gear lubricants are formulated to meet or exceed the highest industry standards so they can help you to overcome these real-world challenges.


What is gear lube used for?

We have engineered our gear oils to offer these performance benefits:

  • Thermal Stability
  • Wear Protection
  • Seal Compatibility
  • Hydrolytic Stability
  • Clean Parts

Alpha HC™ EP gear lube


Castrol Alpha HC EP lubricants have been formulated with carefully chosen synthetic components for excellent performance in applications requiring AGMA (American Gear Manufacturers Association) EP gear oils.

Castrol Alpha HC™ gear lube

This series of ISO grade, technically advanced chemistries excel in applications that require increased oxidation control and thermal stability, consistent anti-wear performance, and low carbon-forming tendencies. Synthetic components provide the potential for extended drain intervals and reduced maintenance costs.



The Castrol Alphasyn T range has been formulated for use in most types of light- to medium-duty enclosed gear systems, but should not be used for heavy or shock-loaded systems. These products are also suitable for bearings and circulatory systems operating at high temperatures, as well as for various applications where a lubricating oil is used under high temperatures, e.g. from hydraulic systems through to large, slow moving gears. All products in the Alphasyn T range have very low pour points and excellent viscosity and temperature characteristics, which allows their use in both low- and high-temperature applications.

Castrol AP Gear Lubricant™


Castrol AP Gear Lubricant is formulated with high-quality base oils and additives that provide excellent load-carrying ability, EP properties, wear resistance, oxidation stability and anti-rust, anti-corrosion and anti-foam properties.

Castrol Axle FD-1 gear lube

This is a semi-synthetic, multi-grade final drive fluid designed to extend drain intervals up to 6,000 hours* in off-road final drives where FD-1 specified fluids are suitable for use. Castrol Axle FD-1 provides excellent wear protection and outstanding oxidation resistance and extends component life.

* with a proper used oil analysis program like Castrol Labcheck

Castrol EP Gear Lubricant


These exceptional quality gear oils are designed for severe-duty applications and offer excellent gear protection. Formulated with selected base oils coupled with an extremely stable sulfur/phosphorous additive package, they are an ideal choice where AGMA EP gear oils are recommended.

CASTROL SYNGEAR™ CD 50 gear lube

This specially formulated synthetic transmission fluid is designed for extended drain and severe service in heavy-duty manual transmissions that require a non-EP gear or transmission fluid. Castrol Syngear CD 50 is formulated from a synthetic base stock with a high-viscosity index and low pour point, and provides superior all-climate, year-round performance. It also contains an anti-wear additive, as well as rust, oxidation and corrosion inhibitors.

Castrol Syngear™ Lubricant


This premium synthetic, heavy-duty, multi-grade gear lubricant meets API GL-5 service. It provides excellent cold weather performance, outstanding stability under higher than normal operating temperatures, and substantial load carrying ability for cooler operation and longer equipment life.