75w90 vs. 80w90 Gear Oils: Understanding the Differences and Making the Right Choice for Your Vehicle
Lubricants and gear oils play a crucial role in the performance and longevity of car components. They protect gears from rust, corrosion, and oxidation, ensuring smooth operation. When it comes to gear oils, different viscosity grades are available, each with its specific applications and benefits. In this article, we will compare 75w90 and 80w90 gear oils to help you determine which one is preferable for your specific needs.
The Importance of Choosing the Right Gear Oil:
Transmission units in vehicles operate at high temperatures, pressures, and speeds, making it crucial to use the proper transmission oil. While some people interchangeably use 75w90 and 80w90 gear oils, it is essential to understand the differences between them. Although these oils share similar components and performance-boosting additives, their viscosities vary, which affects their functionality under different temperature conditions.
75w90 Gear Oil:
What does 75w90 mean? 75w90 gear oil is a synthetic lubricant formulated with synthetic base oils and additives. It is recommended for applications with extreme pressure and performs well in colder climates. 75w90 gear oil is ideal for use in limited-slip differentials, axles, final drives, and heavy-duty manual transmissions. It offers exceptional load-spotting functionality, making it suitable for gearboxes in railway applications that experience surprise loading and high pressures.
75w90 gear oil exhibits an excessive viscosity index (VI), excellent oxidation and thermal stability, low-temperature fluidity, and a low pour point. It has the advantage of low foaming, providing long seal life and maintaining excellent film strength for reliable lubrication.
80w90 Gear Oil:
80w90 synthetic oil serves as a lubricant for non-synchronized manual transmissions in buses and trucks, as well as in extreme-pressure applications. It is recommended for limited-slip and conventional differentials. The “80” in the name indicates its excellent performance in cold temperatures, while the “90” signifies its viscosity or thickness at 100 degrees Celsius. The kinematic viscosity of 80w90 gear oil ranges between 13.5 to 18.4 square millimeters/second. This gear oil offers high shear stability and can withstand heavy loads.
Thinner oils tend to flow more easily in low temperatures, making 80w90 synthetic gear oil multipurpose. It can be used in gears, spiral axles, and certain manual transmissions. This gear oil offers exceptional flexibility, strong resistance to foaming, and effective protection against corrosion.
Differences between 75w90 and 80w90 Gear Oils:
75w90 and 80w90 gear oils may appear similar in liquid form, but they have significant differences in usage, configuration, ingredients, and other factors that may not be immediately apparent. Let’s explore the distinctions between these two gear oils in more detail:
Viscosity:
Viscosity, or thickness, is a notable difference between 75w90 and 80w90 gear oils. Gear oils are known for their viscosity, which helps maintain the proper functioning of axle machinery even in challenging conditions.
SAE 80w90 gear oil, derived from mineral oils, is denser than 75w90 at lower temperatures. Consequently, it requires more frequent oil changes and maintenance. Its thickening at lower temperatures may compromise efficiency.
On the other hand, 75w90 gear oil maintains constant viscosity across a wide range of temperatures, making it more efficient than 80w90 gear oil in both hot and cold climates.
Density:
The thickness and density of gear oils are related, as thicker oils offer better protection. 80w90 gear oil has a density of 0.90, while 75w90 gear oil has a density of approximately 0.86. Thicker gear oils provide superior protection, but they can become clumpy in lower temperatures, affecting efficiency. Despite being thinner, 75w90 gear oil still provides adequate protection in extreme weather conditions, maintaining the efficiency of vehicle parts.
Additives:
Both 75w90 and 80w90 gear oils perform similarly in terms of efficiency and composition. 75w90 gear oil features a unique adhesive packaging that coats gears, preventing wear and tear. It is reliable, non-foaming, and smooth, making it ideal for heavy-duty applications. This gear oil offers high efficiency, withstands extreme temperatures, and provides effective lubrication.
80w90 gear oil is fortified with lubricating and anti-wear agents, which help manage gear wear and tear. It also contains heat control additives that are not commonly found in basic gear oils. 80w90 gear oil is ideal for racing vehicles and other heavy-duty applications where standard oils may not perform adequately.
Operating Temperature:
75w90 gear oil is thermally robust, thermally stable, shear stable, and para-synthetic. It is a multi-grade gear oil suitable for various vehicle drive applications. The best gear oil should be able to function effectively even under extensive ambient temperature ranges, withstanding high temperatures of around 300-350 degrees Fahrenheit.
80w90 synthetic gear oil is more versatile, operating well in both extreme environments. It works effectively in temperatures ranging from -20 to 400 degrees Fahrenheit, making it the recommended gear oil for both summer and winter conditions. With a higher rating than 75w90, 80w90 gear oil provides excellent performance across a wide temperature range.
Uses:
Due to differences in density and viscosity, 75w90 and 80w90 gear oils behave differently in extreme conditions, leading to variations in their recommended uses. 80w90 gear oil is the preferred choice for both summer and winter applications, as it is specifically designed to withstand extreme weather conditions. It can be used in manual gearboxes, agricultural equipment, transaxles, and transfer cases in passenger vehicles, trucks, 4WDs, and light commercial vehicles.
75w90 gear oil, while suitable for a broad temperature range, is particularly effective in higher temperatures. It minimizes premature wear and tear in gear systems operating under high temperatures. This gear oil is recommended for heavy-duty manual transmissions, axles, and final drives.
Price:
The price of gear oil is an important factor to consider. While 75w90 gear oil has a constant viscosity across a wide temperature range, making it more expensive, it offers excellent performance and is worth the investment. The 80w90 gear oil, although less expensive, may require more frequent oil changes and maintenance due to its higher viscosity at lower temperatures.
Conclusion:
Choosing the right gear oil is crucial for maintaining the performance and durability of your vehicle’s components. While 75w90 and 80w90 gear oils share similarities, their differences in viscosity, density, additives, operating temperature ranges, uses, and price should be taken into account when making a decision. Consider your specific requirements, climate conditions, and manufacturer recommendations to select the gear oil that best suits your needs. Remember, using the appropriate gear oil will ensure optimal performance, protect against wear and tear, and extend the lifespan of your vehicle’s gears and transmission.