What type of oils are generally recommended for use in manual transmissions?

The use of gear oils with specific viscosities is generally recommended for manual transmissions due to their unique lubrication properties. Manual transmissions require a lubricant that can withstand high pressures and deliver effective protection to the gearing components and synchromesh systems. Gear oils are specifically formulated to provide enhanced film strength and stability at different temperatures, which is critical in preventing wear and ensuring smooth gear shifting.

These oils are often designated by their viscosity grades, which indicate how well they will perform under a range of operating conditions. A suitable viscosity ensures that the lubricant flows efficiently and maintains protective qualities, particularly under the stress and heat generated during gear changes.

In contrast, while engine oils provide sufficient lubrication for automotive engines, they may not cater to the specific needs of transmission systems. Transmission fluids are primarily designed for automatic transmissions, where the requirements for lubrication and cooling differ from those in manual systems. Hydraulic fluids, while useful in different applications, do not have the properties necessary for effective gear lubrication in manual transmissions.

Thus, using gear oils with specific viscosities tailored for manual transmission applications ensures optimal performance and longevity of the transmission components.