Automobiles have hundreds of complex differentials. These machines help the engine to start and run smoothly. But ultimate maintenance helps to keep these parts in good health to foster a better driving experience.
Lubricant oils play an essential role in keeping these parts in better condition. 75w90 and 80w90 are examples of gear oils. Many car owners find it challenging to tell the difference between these gear oils due to inconsistent information in the manuals.
The main difference between 75w90 and 80w90 is 7w90 has a higher viscosity level than 80w90. 75w90 gear oil is ideal for axle operating at a higher temperature to inhibit premature depreciation.
Keep reading for more insights into the difference between 80w90 and 75w90. The information will also help you avoid using these gear oil interchangeably. Besides that, you’ll get to know which lubricant oil is suitable for differentials and transmission.
Difference between 75w90 and 80w90 Gear Oils
Viscosity Level
75w90 gear oil is constantly thick. The high viscosity level allows the oil to tolerate extreme heat and cold-weather climate. The thickness protects parts operating at an extreme temperature from experiencing premature wear and tear. 80w90 gear oil is a product of mineral oil.
The low viscosity level reduces the productivity of moving parts at extreme temperatures. The gear oil becomes thin at extreme heat to foster premature depreciation. The winner under this category is 75w90 gear oil due to its productivity, safety, and durable services at lower maintenance costs. 75w90 is a better option for axle operating at higher temperatures.
Operating Temperatures
75w90 has stable and robust properties recommendable for all drive applications in the vehicle. The gear oil is tolerant to oxidation and thermal effects. It can tolerate high temperatures of about 300-350F.
80w90 is a more versatile gear oil. The mineral oil is suitable for both icy and extremely hot weather conditions. It is applicable for a temperature range of -20F to 400F. 80w90 is the best oil for winter and summer weather conditions.
80w90 has a higher rating than 75w90 due to its tolerance to both cold and hot conditions. But 75w90 is limited to higher temperatures to minimize premature wear and tear. The winner under this category is 80w90 gear oil.
Gear Oil Density
The density of 75w90 gear oil is about 0.86. It implies that the oil is thicker to provide ultimate protection against wear and tear at high temperatures. But gear oil with high density tends to be clumpy and downgrade the efficiency of drive applications at low temperatures.
The density of 80w90 gear oil is about 0.90. The oil has low density but can still provide ultimate protection to the gears. The thin gear oil is suitable for working under extreme conditions with low maintenance costs.
75w90 is the winner under this category due to its higher density rating than 80w90. The thickness enables drive applications to withstand the higher operating temperatures.
Additive Properties
75w90 contains a specific adhesive that coats the gears to prevent premature wear and tear. These adhesives make the oil sleek, non-foaming, and reliable for heavy-duty applications.
The additives also make the axle tolerate extreme temperatures without lacking lubrication. 80w90 contains particular anti-wear and lubricating additives. These properties help to manage depreciation in all racing cars and other heavy-duty applications.
These additives have unique heat control properties. Both 75w90 and 80w90 are winners under this category. They are incredible for both heavy-duty and high-performance equipment. Thanks to the special anti-wear and lubricating agents.
Gear Oil Price
75w90 has a constant viscosity over a wider spectrum of temperature. The oil is thicker in extremely high temperatures and thinner in low temperatures. These dynamic properties make 75w90 a little bit expensive. 80w90 has a low viscosity level regardless of the temperature change.
The oil is thin in both high and low temperatures fostering a higher depreciation rate. The constant properties make 80w90 relatively affordable. 75w90 is super expensive and worth the value of your money.
The gear has better ratings to emerge as the winner under this category. It is the best option for heavy-duty machines operating under higher temperatures to minimize wear and tear.
Can You Mix 75w90 and 80w90?
Yes. You are fine to mix 75w90 and 80w90 since they don’t contain weird additives that would downgrade the performance of your drive applications.
Is 75w90 better than 80w90?
Yes. 75w90 is a synthetic oil with a constant viscosity level over a broad spectrum of temperatures. It is ideal for running drive applications under high temperatures due to its ability to manage wear and tear.
Conclusion on 80w90 vs 75w90
75w90 has a higher viscosity level than 80w90. Higher viscosity gear oils can tolerate higher temperatures than lower viscosity gear oils. 75w90 oil provides maximum protection to gears against wear and tear.
But 75w90 gear oil becomes clumpy at lower temperatures and downgrade the performance of the gears. The best option under this circumstance is 80w90 gear oil.
The lubricant oil can withstand icy and hot conditions. Both 75w90 and 80w90 gear oils are the best to consider. These oils guarantee maximum protection to drive applications against premature depreciation. But 80w90 gear oil is less effective to provide protection when the temperatures are high.

Robert Anderson is a world class motorhead who rebuilt his first carb at age 10, his first engine at age 15, and completed his first full hotrod build when he was just 18! Previously, he has ran a part warehouse, delivered pizzas, and managed the service department for a $20 million/year revenue dealership. Robert knows cars like few others and he is passionate about sharing his knowledge.