Shear stress is created from the teeth of metal gears being applied to the metal face of other gears in a parallel form. These gear faces are under the full force of the engine's power in a manual transmission or differential. These components translate this power to the wheels at the desired speed depending on how the gears are applied. In order to protect the faces of these gears over time, gear oil must act as a lubricant and provide protection to these metal surfaces. It's viscosity rating is normally higher than that of regular motor oil, and it's molecular, strength level must stay consistent between drain intervals. If manual transmission or differential oil can not withstand these extreme pressures and temperatures from shear stress, pitting and scoring on the faces of these metal gears will occur. This wear will create metal flake and fluid contamination which will only cause more wear. The cycle will continue to repeat itself until part failure will ultimately occur. Synthetic manual transmission and differential oil lowers the chance of this occurrence because of it's powerful properties.

Conventional, petroleum based oils break down quickly from shear stress and the extreme temperatures caused by gear frictions. Their irregular molecular structure created in the refining process can not withstand these conditions well between drain intervals. They thin quickly and allow the metal faces of gears to grind on one another. Synthetic fluids are created in a laboratory to possess more specific properties such as viscosity and a uniform molecular structure. Because it is chemically engineered for a specific composition, the power of synthetic manual transmission and differential oil is much better suited for these purposes. It withstands these extreme stresses, temperatures, and frictions better than traditional oils. These synthetic fluids also contain special, high pressure and anti-wear additives that protect and clean these vital metal parts. These additive rich, synthetic fluids cope better under the intense, gear pressures present in manual transmissions and differentials.

Although just as helpful and necessary for protection in ordinary vehicles, synthetic manual transmission and differential oil is especially helpful in those used for racing, hauling, and towing. These applications create the largest loads and stresses on the gears of these components. The financial savings created from better protecting these components in both regular applications and those used more for specific purposes is clearly demonstrated in longer drain intervals, fewer part repairs, and better performance. Amsoil, one of the leading producers of synthetic oils, offers a wide range of synthetic manual transmission and differential oils at competitive prices, including their Synthetic Manual Synchromesh Fluid which can be used in all automotive applications requiring synchromesh transmission fluid. Without question or exception, the power of synthetic protection in manual transmissions and differentials proves superior to traditional fluids every time.