75w85 Vs 75w90: Comparison, review and guide

You always want your car to be operational, so you must repair faulty components and lubrication over time.

The lubricants assist the engine in working better and protect the details from wear and tear, rust, corrosion, and oxidation.

75w85 vs 75w90

If you’re planning to replace your vehicle’s engine oil, you’ve probably come across the 75w85, and 75w90 engine oils, which are the most popular and can be used in all weather conditions.

So, we’ve compared the 75w85 Vs 75w90 engine oils below so you can make an informed decision when selecting gear oil for your vehicle.

What is 75w85 Gear Oil?

75w-85 is a synthetic oil used in many vehicles, including cars and trucks. The 75w85 engine oils is also known as API CK-4. And it’s also used for marine engines, generators, and other high-powered machines.

The main reason why it’s so popular is that it lasts longer than conventional oils. 75w-85 has a higher API gravity rating than traditional oils, which can provide better protection over time.

75w85 base Oil is designed to reduce friction and wear in internal combustion engines. It has a light viscosity index, which can flow easily through the system.

This makes it perfect for cars that run long distances daily, such as SUVs or trucks.

What is 75w90 Gear Oil?

75w90 Gear Oil is a medium-viscosity synthetic base oil primarily used in diesel engines. It has a higher viscosity grade of 90.

It’s formulated to provide optimum performance for your vehicle, with improved fuel efficiency and extended drain intervals compared to previous formulations.

It also contains anti-wear additives, which help prevent metal wear during long-term operation.

It’s considered an “extreme” grade of motor oil because it has a high viscosity index and can withstand very high temperatures.

It’s also formulated with a special additive package that allows it to stay cleaner on your engine than other oils.

75w85 Vs 75w90 Gear Oils Comparison

Name 75w85 Engine Oil 75w90 Engine Oil
Lower Viscosity 75 75
Higher Viscosity 85 90
Oil Thickness Thin Thick
Fuel Economy Good Good
Engine Wear Moderate Less
Suitable Weather All Weather All-Weather
Ideal Temperature -40 to 45 degrees celsius -40 to 50-degree celsius
Oil Base Synthetic Synthetic
Additives Yes Yes
Life Expectancy 70,000 miles 50,000 miles
Replacement Required 65 to 68 thousand miles 48 to 49 thousand miles
Anti-Corrosion Yes Yes
Anti-foam Yes Yes
Anti-Wear Yes Yes
Vehicle Compatibility Petrol, Diesel, and CNG Petrol, Diesel, and CNG
Ideal Engine Light duty and high-performance engines Light duty and high-performance engines
Friction Least Moderate
Thermal Stability Good Good
Oxidation Stability Good Better

Similarities Between 75w85 Vs 75w90 Gear oil

The 75w85 and 75w90 engine oils can be used in various vehicles. However, they are best suited for heavy-duty vehicles.

There are many similarities between these two engine oils, making it difficult for us to choose the finest one.

Lower Viscosity

The first thing to know about these two engine oils is that they have a low viscosity. The 75w85 and 75w90 have the same viscosity grade of 75.

The lower viscosity of these two engine oils allows oil to flow easily and effectively between engine components, allowing your engine to run smoother and perform better.

Because of these lubricants, the engine will take less energy to generate more power.

Fuel Economy

Regarding fuel economy, both engine oils will provide equivalent results because they are comparable and the same.

Both give the slightest friction between engine components, allowing the engine to function more smoothly and efficiently.

Hot and cold Weather Conditions

Harsh Weather conditions is one of the most crucial factors to consider while selecting engine oil. The best thing about these two engine oils is that they can operate in any weather(I mean in both hot and cold weather).

These two engine oils will provide the most satisfactory performance whether you live in a snowy location with cold weather, a hot region, or any other climate region.

Oil Base and Additives

Both the 75w85 and 75w90 gear oils have a synthetic base. Apart from the oil base, both of these oils have many extra additives that add anti-foaming, anti-corrosion, and other protective properties.

Anti-Corrosion Properties

Both 75w85 and 75w90 contain corrosion inhibitors, which are intended to protect the engine from corrosion produced by organic or mineral acid created during oxidation.

Anti-Wear and Anti-Foam

Anti-wear and anti-foaming additives are included in the 75w85 and 75w90 engine oils. This means that your engine’s components will experience the least wear while moving.

Moreover, the anti-foaming agents will avoid any foaming, which will reduce the air to keep your engine safe.

Vehicle Compatibility

The 75w 85 and 75w90 fully synthetic gear lubricant ideal gear oil are compatible with petrol, diesel, and CNG vehicles.

But both of them are highly suitable to use in a diesel engine, and both do not perform ideally when used in CNG vehicles.

Compatible Engines

Regarding engine compatibility, the 75w 85 and 75w90 engine oils is compatible with light and heavy-duty engines. They both are ideal to use with high-performance engines like SUVs and trucks.

Thermal Stability

Both engine oils shares the same amount of thermal stability. Both the 75w 85 and 75w90 synthetic gear oil are highly stable in most conditions, and you will not have any thermal throttling with these engine oils.

Difference Between 75w85 Vs 75w90 Gear oil

The 75w85 and 75w90 gear oils have many similarities, but there are also some significant distinctions that differentiate these two engine oils.

Higher Viscosity

The natural viscosity of engine oils indicates its thickness. In this comparison, 75w90 motor oil is slightly thicker than 75w85 engine oil.

This is because it has a higher viscosity grade of 90, as opposed to an 85 higher viscosity grade of 75w85 gear oils.

Engine Wear

Engine wear is different in both of these engine oils. The 75w 85 is a bit of a downgrade and will cause more engine wear because it is thinner.

In comparison to the 75w90, it will have a negative influence on the engine over time.

Temperature Range

The temperature ranges of 75w85 and 75w90 differ slightly, although not significantly.

The 75w85 motor oil has a temperature range of -40 to 45 degrees Celsius, whereas the 75w90 motor oil has a temperature range of -40 to 50 degrees Celsius.

Life Expectancy and Replacement Time

In comparison to the 75w90, the 75w85 has a greater life of around 70,000 miles.

You should replace the 75w85 after you have driven 65 thousand miles or more and the 75w90 when you have driven 48 thousand miles or more.


Both engine oils have the least friction, although 75w90 has slightly greater friction due to its higher viscosity.

Oxidation Stability

When it comes to oxidation stability, 75w85 is a good option but not the best. The 75w90 is the superior choice because it has better oxidation stability.

Pros and Cons of both these gear oils

75w85 Gear Oil:

Pros Cons
Better performance Average life and replacement time
Excellent or better fuel economy More engine wear
Least amount of friction
Compatible with high-performance engines

75w90 Gear Oil:

Pros Cons
Great oxidation stability Poor oxidation stability
Less engine wear
Excellent life
Better replacement time

Which is Best: 75w85 Vs 75w90 Gear Oil?

The 75w90 is a better choice, in our opinion. This is because this engine oils offers great oxidation stability when compared to 75w85. Moreover, it has less engine wear and will last longer than other regular engine oils.

On top of that, it has a greater replacement time of about 70,000 miles, making it the best engine oil.

Read: 5w40 vs 10w40

Frequently Asked Questions:

Can you use 75w85 instead of 75w90 or vice versa?

Yes, you can use 75w85 instead of 75w90 and vice versa.

Which has a better heat resistance: 75w85 Vs 75w90?

The 75w90 has a better heat resistance as it has a higher viscosity.

Can you mix the new oil with the old one?

No, it is not recommended. This is because the old oils lose their properties, such as anti-foaming, anti-corrosion, and others.


Hopefully, the 75w90 Vs 75w85 gear oils comparison added to your engine oils knowledge. Both engine oils are nearly identical, with few significant variances in better .

However, when it comes to selecting the best between the two oils, the 75w90 gear oil is our choice and is the top notch base oils.

This gear oils outperforms the 75w85 in terms of oxidation stability, life and replacement time, innovative manufacturing techniques , precise and thorough tests and natural viscosity.

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