Difference Between 75w90 vs 75w140 Gear Oil

You just installed some new gears. Now, which one should you use between 75w90 vs 75w140? Which should you buy? Which one do you think is the better option?

Gear oil can be a confusing topic. There are many different types of oil, and not all are created equal. You may have heard of the 75W90 and 75W140 gear oils. You may think that the W refers to watts, but it’s a number that refers to the viscosity. The higher the number, the thicker the oil.

You need to choose the right gear oil for your gears. We’ll help you pick the best oil, whether you have 75W90 or 75W140.

Difference Between 75w90 And 75w140 Gear Oil

75w90 gear oil is a heavier gear oil grade designed for use in vehicles with automatic transmissions. 75w140 gear oil is a lighter gear oil grade designed for use in cars with manual transmissions.

Both oils are used in all types of automatic and manual transmissions, but 75w90 gear oil is recommended for use in vehicles with automatic transmissions because it can protect the transmission and other parts of the engine from overheating.

There are two types of gear oils: regular gear oil and synthetic gear oil. Regular gear oil is made from petroleum products and is generally used in manual transmissions.

Synthetic gear oil is made from polymers and is usually used in automatic transmissions.

Regular Gear Oil vs. Synthetic Gear Oil Synthetic gear oil is much more expensive than regular gear oil. It costs about 30 percent more than regular gear oil.

Recommended Gear Oil

About 75w90 Gear Oil

This type of oil is designed for heavy-duty engines, such as those used in construction and heavy equipment. It is made of high-quality oil and is intended to provide long-term protection for the engine.

75w90 Gear Oil is a special lubricating oil meant for use in gear systems. This oil is intended to protect the gear system components from wear and tear, including heat.

In addition, this oil helps prevent the formation of metal shavings in the gear system.

The oil is suitable for vehicles, farm machinery, heavy-duty machinery, industrial machinery, and other applications where high-load gears are used.

This oil can be used in manual transmission systems and automatic transmission systems.

Valvoline SynPower SAE 75W-90 Full Synthetic Gear Oil 1 QT

We are always on the hunt for the best gear oil, especially since it’s one of the most critical fluids you’ll add to your vehicle.

It is not just the difference between a well-performing engine and an under-performing one, but it can also mean the difference between a smooth driving experience and a rough one.

That’s why we have put together this list of the best gear oils that will help improve your vehicle’s performance and protect it throughout the years.

Valvoline SynPower SAE 75W-90 Full Synthetic Gear Oil 1 QT. This is the best gear oil for conventional and limited-slip differentials and non-synchronized manual transmissions.

It’s specially formulated to maintain excellent low-temperature fluid protection, and it helps provide outstanding thermal stability for cleanliness and longer service life.

It contains special additives to assist in protecting gear teeth from rust and corrosion and reduce chattering in limited-slip differentials.

The SynPower SAE 75W-90 gear oil is recommended for conventional and limited-slip differentials and non-synchronized manual transmissions where API GL-5 or API GL-4 fluid is specified.

This is one of the best gear oils we’ve ever tested, and we’re excited to share it with you.

Good & Bad

Pros

• Can be used for all types of differentials.
• It is not a single-use product.
• It doesn’t need to be changed after every use.
• Affordable

Cons

• Not compatible with all differentials.

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Red Line 57904 (75W90) Synthetic Gear Oil – 1 Quart

Red Line has been a top name in gear oil for decades. They’re known for their high quality and durability and their ability to withstand extreme temperatures without going rancid. With so many different applications for their gear oils, you can ensure that they’re engineered to last.

The 57904 is a 75W90 gear oil, which means it offers excellent lubrication for various applications.

It also features a high-quality additive package that’ll help keep your engine running smoothly. This includes anti-wear additives for the transmission, friction reducers for the limited-slip differential, and a full complement of other additives to keep everything running smoothly.

Red Line is famous for the longevity of its products, and the 57904 is no exception. It’s rated to go up to 125°F, so it’s designed to work in high-temperature environments and with the extreme performance levels of modern vehicles.

If you want an oil that can handle the extreme conditions of modern vehicles, and you don’t want to spend a fortune, then this is the one for you.

Good & Bad

Pros

• Highly durable.
• Easy to use.
• Compact, lightweight, and portable.

Cons

• Not as effective as other gear oils.

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Royal Purple 01300 Max Gear 75W-90 High-Performance Synthetic Automotive Gear Oil, 1 Quart (32 Ounces)

Royal Purple’s Max-Gear is an excellent option if you need a quality gear oil that doesn’t compromise performance. It has the best formula of any of their gear oils, and it can help your transmission run better than ever.

It provides the highest levels of protection against metal corrosion and friction and can be used for most vehicles that require a gear oil.

It’s compatible with many types of vehicles, and it comes with a 30-day money-back guarantee.

The best part? It’s straightforward to use – all you have to do is add it to your gear oil and use it for maintenance.

It’s designed to last for years without having to change it, and this is precisely what you want from a quality gear oil.

Good & Bad

Pros

• works great as a gear oil
• has a long life cycle
• Very affordable
• Non-corrosive

Cons

It has a long list of ingredients

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Lucas Oil 10121 Synthetic SAE 75W-140 Gear Oil, Red, 1 Quart (32 Ounces)

The Lucas Oil 10121 Gear Oil is the best gear oil for high-performance applications. It has a low viscosity and a high flash point, which means it will stay slick for a long time.

It can even withstand extreme temperatures while remaining very lubricious. It also has a high viscosity index, which means it’s not prone to thinning out when exposed to heat.

This makes it very versatile and helpful in a variety of situations. It also stands up well to the demands of high-performance applications, such as racing, where it can remain slick and durable even after hours of operation.

You won’t have to worry about changing your oil more often than necessary with its outstanding performance. You can use this in cars and motorcycles, but it’s especially great for vehicles with over 600 horsepower.

It’s an excellent choice for both street and track use. It’s also safe for most engines, including gasoline, diesel, and even natural gas.

Good & Bad

Pros

• Provides superior lubrication
• Keeps the gears of your bike oiled.
• Inexpensive and easy to use.
• It can be used on all types of bikes

Cons

• Not environmentally friendly.

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Lucas 10122 75/140 Synthetic Gear Oil – 1 Gallon

Lucas has been one of the leading lubricants manufacturers for years now, and their gear oils are some of the best on the market.

They offer three types of gear oils: Gear Oils, Gear Lubricants, and Hydraulic Lubricants. Gear Oils are designed for heavy-duty applications, while Gear Lubricants are ideal for everyday use.

The Lucas 10122 75/140 gear oil is excellent for heavy-duty applications. It’s designed to stand up to high temperatures and ensure long life.

It’s also one of the only gear oils that can be used with synthetic and conventional gears. This means you can get outstanding performance from your standard transmission without compromising lubrication.

Lucas gear oils have been tested against other leading gear oils to ensure they stand up to extreme conditions. Lucas Gear Oil has been proven to stand up to temperatures as high as 450°F (230°C) for over ten years!

In addition to being super-lubricant, it also comes in a convenient 1-gallon bottle. It’s also designed for easy application and comes in a specially formulated grease gun.

This is an excellent choice for anyone looking for a top-quality gear oil that will stand up to high temperatures and last long.

Good & Bad

Pros

• has a long shelf life.
• Easy to use.
• It is non-toxic and biodegradable.
• Made from renewable materials.
• Not harmful to the environment.

Cons

• Expensive.
• It is hard to find.

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Red Line 57914 75W-140 Gear Oil – 1 Quart

If you’re into street-driving cars or racing, then you need to make sure your differential gears are in good shape.

A worn-out differential can cause all sorts of problems, so it’s crucial to get your differential checked regularly.

The Red Line 57914 75W-140 Gear Oil is an excellent replacement for a worn-out differential.

It has a GL-5 rating, which means it’s designed to work in both limited slip and conventional units. This means you’ll be able to get your vehicle back on the road as soon as possible.

Red Line is an American company that makes some of the best gear oils for the most popular brands of automobiles.

Their products are also well-regarded for their durability, which is why top automotive magazines and websites have recommended them.

We’re not just recommending this product because it’s an American brand; the quality of the oil is excellent.

It features a high-quality formula with a long lifespan, making it the perfect choice for streetcars or racing vehicles.

The oil is also compatible with all differentials, so you don’t have to worry about getting one wrong. It has a 1-quart capacity, so you can keep enough to last for some time.

Good & Bad

Pros

• easy to use
• inexpensive.
• Lasts a long time.
• It doesn’t need to be changed as often.
• It is suitable for all types of vehicles.

Cons

• Not easy to clean
• It isn’t compatible with automatic transmission.

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What Does The Number Mean In Gear Oils?

The number in a gear oil’s ingredient listing indicates how much of that particular oil is in the product.

If the number is less than 50 percent, then that means it is a blend of two or more oils. If it is 100 percent, then that oil is the only one in the product.

For example, if you look at Mobil 1 Synthetic Gear Lubricant, you will see this: In the above example, the number indicates that Mobil 1 is the only oil used in the product.

It also has to say “100 percent” on the label.

Monograde Gear Oils

Monograde Gear Oils are explicitly made for gears and other rotating machinery. They are made of high-quality synthetic oil and are designed to provide long-lasting performance.

Monograde Gear Oils are suitable for use in various applications, including marine, industrial and automotive.

They are also ideal for use in home-based appliances. Monograde Gear Oils can be used in both new and existing machinery and offer a cost-effective solution for maintaining machinery.

They can be used to lubricate and cool internal components and prevent rust from forming on the parts of a machine.

A wide variety of oils are available, so you can find one that suits your requirements.

When Can Each Oil Be Used?

The Viscosity Of Gear Oils 

Viscosity oil can be used when the motor is hot or cold.

It should not be used only when the motor has not been run for an extended period.

When the engine is warm, viscosity oil will flow more quickly than at room temperature.

This is because the viscosity oil is thicker at room temperature. When the engine is excellent, it is hard to tell if the viscosity oil is thick or thin.

Additives Oil 

Oil additives are chemical compounds that are added to the base stock. They enhance oil properties, such as its lubrication and anti-corrosion properties. These additives can also be used to reduce engine deposits and improve combustion.

Oil additives are often classified into extreme pressure additives (EP) and anti-wear additives (AW).

Oil additives are used in different types of oil, depending on their application. For example, engine oil is formulated with EP additives to help increase the life of internal engine parts. It also helps protect these parts from wear.

The additive can also help prevent water and dirt from corroding the metal surfaces of internal engine parts.

On the other hand, synthetic motor oils are formulated with AW additives because they help reduce friction between moving parts.

They also help keep the moving parts clean. There are many different kinds of additives available. Most of them have their properties and benefits. 

Base Oil Type

Base oil type can be used at any time during the manufacturing process.

Base oils are used in various applications, from lubrication to fuel blending and even as an ingredient for some specialty chemicals.

How do they work? The purpose of base oil is to provide several different properties. The most crucial property of base oil is viscosity. This viscosity affects how it will behave when it is used.

75w90 Vs. 75w140: The Comparison Between Them

1. Viscosity

The viscosity of the 75w90 oil is approximately 3000 cP.

When heated to about 130°F (54°C), it becomes a fluid, and if allowed to cool, it will go back to a solid. This oil is very high quality, made from the best available crude oils. It has been carefully blended to give you the best possible consistency at room temperature.

The viscosity of the 75w140 oil is approximately 1,000 centipoises.

That’s a lot, but not too much for a diesel engine, which is why it’s so popular with off-road and racing applications. It’s also important to note that the viscosity is measured at 100°C (212°F).

1. Fuel Economy 

The 75w90 oil has a higher API gravity than the conventional motor oil, which means it is heavier.

This means that it will take longer for the oil to flow through an engine, decreasing fuel economy.

The 75w140 oil has a fuel economy of approximately 5.0 miles per gallon.

2. Application

The most common use for 75w90 oil is in manual and automatic transmissions. It is also used in engines, including gasoline, diesel, and electric vehicles.

The 75w140 oil is best used in engines requiring lightweight oil and low viscosity. It is also recommended for use in air-cooled engines.

3. Operating Temperature

The operating temperature of the 75w90 oil is between 300°F to 350° degrees Fahrenheit.

The average operating temperature of the 75w140 oil is between 50°F and 100°F.

4. Pricing

The price of the 75w90 oil is around $12.98 per quart.

A 75w140 oil can vary depending on where you purchase it. However, on average, a 75w140 oil can cost around $17 per bottle.

 Compatibility on Some Cars/Models

The compatibility of 75w90 and 75w140 gear oil on some cars and models can vary depending on the type of engine oil and vehicle.

Generally, the oil should be compatible with both oils, but some exceptions may be.

The 75w90 gear oil is designed to work in vehicles with high compression engines such as those found in most large pickup trucks and SUVs.

This oil is not recommended for use with engines that have a low compression ratio.

The 75w140 gear oil is designed for use in vehicles with engines that have a low compression ratio. Both oils are compatible with most passenger car engines.

Basic Knowledge of Gear Oil

Gear oil is a lubricant used in many different types of machinery.

Gear oil is a type of oil used to lubricate gears to keep them running smoothly. Gear oil is also used to help preserve the gears.

If your gear oil is no longer functioning, you may be able to replace it. Gear oil is usually a thick, dark liquid, and it is often odorless.

The viscosity of gear oil can vary, so you must use the correct type for your application.

Some gear oils are designed for manual transmissions, while others are made specifically for automatic transmissions. It is essential to know the type of gear oil you need and the viscosity level.

FAQS

Which is better, 75w90 or 75w140?

There is no definitive answer, as both oils are excellent choices for automotive use. Ultimately, it depends on the exact specifications of the engine and other components being used.

Is Thicker gear oil better?

There is no definitive answer, as different oils perform differently under various conditions. Ultimately, it depends on the application and intended use of the oil.

What is 75w140 used for?

75w140 is a medium-grade, low-chromium, all-purpose oil used in various industrial and consumer products. It is trendy in lubricants, automobile parts, and plastics.

Which is the best gear oil?

There is no one best gear oil. Different oils are better for various applications. Some oils are designed for high-speed gearboxes, while others are better for manual transmissions.

Can I use 75w140 instead of 75w90?

You can use either oil. However, using a higher-viscosity oil will result in a smoother ride and less noise.

Can you mix gear oil weights?

Yes, you can mix gear oil weights. However, it is essential to use the correct gear oil for the application.

Conclusion

75w90 vs. 75w140 – Which One Should You Pick?

It would help if you started with 75W90 and then moved up to 75W140 once there was enough traffic.

I recommend following my advice and going with the 75W90 option because it’s a bit easier to find a good-quality product to promote. This is also what I did when I first started, and I still use this approach today.

If you are interested in moving to 75W140, you should go for the top-ranked products available on the marketplace. The problem with this is that they are usually too high-priced for most people.