What is the difference between 75W90 and 80W90 gear oil?
When it comes to maintaining your vehicle's transmission or differential, choosing the right gear oil is crucial. Two common options you might encounter are 75W90 and 80W90 gear oils. While they may seem similar at first glance, there are key differences that can impact your vehicle's performance and longevity. In this article, we’ll break down the distinctions to help you make an informed decision.
Understanding Gear Oil Grades
Gear oil grades, such as 75W90 and 80W90, are defined by the Society of Automotive Engineers (SAE) and indicate the oil's viscosity at different temperatures. The numbers and letters in these grades provide important information:
- The first number (e.g., 75 or 80): This represents the oil's viscosity in cold temperatures. A lower number means the oil flows more easily in cold weather, which is beneficial for cold starts.
- The "W": Stands for "winter" and indicates the oil's performance in low temperatures.
- The second number (e.g., 90): This indicates the oil's viscosity at high operating temperatures. A higher number means the oil maintains its thickness better under heat and stress.
In summary, these grades help you understand how the oil will perform in both cold and hot conditions, ensuring your vehicle's gears are properly lubricated and protected.
Key Differences Between 75W90 and 80W90
While both 75W90 and 80W90 are multi-grade gear oils designed for a wide range of temperatures, they differ in their cold-temperature performance and applications:
- Cold-Temperature Performance: 75W90 has a lower cold-temperature viscosity compared to 80W90. This means it flows more easily in colder climates, making it ideal for vehicles operating in regions with harsh winters.
- Applications: 75W90 is often recommended for modern vehicles with tighter tolerances and advanced gear systems. On the other hand, 80W90 is commonly used in older vehicles or heavy-duty applications where extreme cold performance is less critical.
- Fuel Efficiency: Due to its lower viscosity at cold temperatures, 75W90 can contribute to slightly better fuel efficiency, as it reduces drag on the gears during startup.
These differences make it important to consider your vehicle's specific needs and the climate in which you drive when choosing between these two gear oils.
When to Use 75W90 or 80W90
Here are some general guidelines to help you decide which gear oil is right for your vehicle:
- Choose 75W90: If you live in a region with cold winters, drive a modern vehicle, or prioritize fuel efficiency.
- Choose 80W90: If you live in a milder climate, drive an older vehicle, or need a gear oil for heavy-duty applications like towing or off-road driving.
Always consult your vehicle’s owner’s manual or a trusted mechanic to ensure you’re using the correct gear oil for your specific make and model.
Conclusion
Both 75W90 and 80W90 gear oils are excellent choices for protecting your vehicle’s gears, but their differences in cold-temperature performance and applications make them suited for different scenarios. By understanding these distinctions and considering your driving conditions, you can make the best choice for your vehicle’s needs. If you’re still unsure, don’t hesitate to reach out to a professional mechanic for advice. At Kevin’s Autos, we’re always here to help you keep your car running smoothly!
Frequently Asked Questions
What is 80w90 gear oil used for?
The 80W-90 gear oil can be used in extreme pressure conditions and as a lubricant for some non-synchronized manual transmissions in heavy-duty trucks or buses.
Which is better, 75W80 or 75W90?
At 75W90 the kinematic viscosity is 13.5 to 18.4 mm²/s. 75W90 offers better shear stability than 75W80 and can generally withstand higher loads in the transmission. Oils of different SAE classes can be mixed with each other.
What's thicker than 75W90?
So, the difference between "75W90" and "75W140" is that at operating temperature, the 75W140 will be considerably thicker than the 75W90 but at room temperature they will be about the same viscosity.
Is thicker diff oil better?
Using thicker oil:
Better acceleration. Increases on-power steering (reduces understeer) Better suited on high-bite, smooth tracks. Too thick oil gives more over steer.
What is the temperature range for 75W90 gear oil?
300°F to + 350°F. Excellent seal compatibility and increased seal life.
Can I use 75W90 gear oil instead of 80w90?
75W-90 is fine. The only difference between 75W-90 and 80W-90 is the cold flow characteristic, 75W will flow faster. Both are 90 wt at operating temperature. You can use Severe Gear 75W-90 in the front, I do. Or you can save a few $$ and use this since the front axle sees less use.
What is 75w-90 used for?
Product Description. Mobil Synthetic Gear Oil 75W-90 is a fully synthetic gear lubricant formulated from synthetic base oils and an advanced additive system. It is designed for use in many railway gearboxes and provides excellent load-carrying capability where extreme pressures and shock loading are expected.
Is 80W thicker than 75W?
SAE 75W-90 maintains a more consistent thickness, or viscosity, across a wide temperature range. It's thicker when exposed to high heat and thinner under colder, wintry conditions than 80W-90. The use of 75W-90 gear oil is recognized by OEMs as a contributor to overall fuel economy.
Which grade gear oil is best?
The American Petroleum Institute (API) has established standards for gear oil performance. Look for the API classification on the product label, such as API GL-4 or API GL-5. The API GL-4 is suitable for lower torque, synchromesh transmissions, while API GL-5 is designed for higher torque, hypoid gear systems.
Is 75W90 the same as 10W40?
75W90 corresponds to 10W40 motor oil in absolute viscosity. That's why a common mistake is to think a transmission fluid is thicker (has a higher viscosity) than it actually is. One more API classification for gear oils is MT-1.
