75w90 Vs. 75w140: Find The Best Bang For Your Buck

One of the most challenging battles we can see is 75w90 vs. 75w140 when choosing the best gear oil. Also, we can’t compromise when it is about protecting the vital components of our gear. And if your oil does not perform in industrial gearboxes, there will be no point in getting satisfaction.

Here both the oils work great in differentials, transfer cases, and other properties. Most importantly, you will get rid of critical internal components inside your engine.

You must have heard about 75w90 vs. 75w140 mustang. This term is the subject where we most often can’t judge out the correct one. For this reason, I will help you with which one will be a better choice for your vehicle and which one will be not. So, I was hoping you will not go anywhere and glance at my article to find the best one.

Comparison Table: 75w140 vs.75w90

Comparison Parameters75w9075w140
Kinematic viscosity[mm2/s]115 @ 40° C and 15.2 @ 100° C172.4 @ 40° C and 24.5 @ 100° C
Viscosity Index           138174
Low Shear Rate Viscosity4.44.4
High Shear Rate Viscosity  
Temperature Range300 °F to 350 °F-40° F and above
Density[g/cm3]878 kg/m3869 kg/m3
Oil FlowFlows well in coldIt can’t wash well in cold

The Top 4 Best 75W90 Oil Lists

#1. Valvoline SynPower Full Synthetic Gear Oil

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In the root of ultimate protection and performance, Valvoline SynPower works as you think. There is a thermally stable gear lubricant of extreme pressure, making it easy to protect and operate in high and low extreme-temperature conditions.

Differentials like limited-slip hypoid can have a tremendous handy from SynPower Gear Oil. Here, the formulation maintains excellent low-temperature fluid protection and gives longer service life.

Rust and corrosions will not even touch your engine due to the special additives which reduce chatterings.

If you are looking for a non-synchronized manual transmission, then you must have a look at Valvoline’s oil. This product will serve you up to the mark in getting a friction modifier at a reasonable price.

Lucas SAE 75W-90 Synthetic Gear Oil

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Lucas SAE 75W-90 Synthetic Gear Oil is a long-lasting, super slick, non-foaming lubricant designed for heavy-duty applications. While looking for high performance of your engine, this oil can be the best option. The special additives here make the package cushion gears and desist from squeezing out.

You don’t have to stress about losing the lubricity. The unique design of the oil makes it stand up even in high temperatures. Moreover, the weight is not so heavy, only 3.447 kilograms. For manual transmissions, rear diff, and transfer case, you must try this oil.

And guess what? This product will not let your engine make noise and lubricate smoothly. Whenever you need a thicker texture, Lucas Oil will not disappoint you at all.

Royal Purple Max Gear Synthetic Automotive Gear Oil

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Max Gear is recommended for rear differentials or automotive front and lower gear units of marine engines. It has soft yellow metals like brass, bronze, copper, and others, including non-corrosive substances and a safe synchronizer.

You can extend the gear and bearing life with the help of Max Gear which provides superior protection over conventional and synthetic gear oils. This automotive hypoid gear oil maximizes power throughout the drivetrain and gives protection to heavily loaded gears.

Max gear can make any equipment run quieter, more relaxed, smoother, and longer without overhauls. And if you are cautious about environmental friendliness, this oil can serve you all with the fulfillment of warranty requirements.

Red Line 57904 Synthetic Gear Oil

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Red Line gives thousands of applications for passenger cars, racing vehicles, and light trucks. Here, you will get additional friction modifiers for suitability with clutch-type differentials. But it will be hard for transaxles in passenger vehicles or manual transmissions.

If you are looking for a faster shift, I recommend you to give a check on Red Line’s product. Moreover, it makes the transmission synchronizers equivalent to speeds more quickly. You can also use this oil for racing limited-slip differentials to give your synthetic gear utmost excellency.

Other than that, you will get a transfer case that makes the rear end survive for a long time. So, stay tense from all the hesitation that might cause danger to your engine predominantly.

Valvoline SynPower Full Synthetic Gear OilOperates in both high and low extreme-temperature conditions
Protects engine from rust and corrosion
Maintains excellent low-temperature fluid protection
Works as the best friction modifier
Lucas SAE 75W-90 Synthetic Gear OilSuperslick, long-lasting and non-foaming
Ensures high performance of the engine
It does not let the lubricity lose
It stands out even in high temperatures
Suitable for heavy-duty applications
Royal Purple Max Gear Synthetic Automotive Gear OilBest for lower gear units of marine engines
Provides superior protection throughout
Maximizes power in the drivetrain
It makes any gear run quieter, more relaxed, smoother, and longer
Has absolute environment-friendly properties
Red Line 57904 Synthetic Gear OilContains additional friction modifiers for suitability
It gives a faster shift in all way
It makes transmission synchronizers equivalent to speeds
Best for racing limited-slip differentials
It makes the rear end survive for a long time

The Top 4 Best 75W140 Oil lists

Valvoline SynPower Full Synthetic Gear Oil

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Valvoline SynPower Full Synthetic Gear Oil has all the properties of performance and ultimate protection. There is a thermally stable extreme pressure gear lubricant that protects in both high and low extreme-temperature conditions. Also, the operation is effortless. The manufacturers recommend it, especially for limited-slip hypoid differentials.

Moreover, you will find great compatibility of this oil with your gear lubricants. And the special additives in this oil will assist in protecting your gear teeth from corrosion and rust. If there is any chattering in the engine, this Vavoline’s product will reduce that as well.

Those who want to maintain their vehicle profoundly can look at this oil. Nonetheless, it will be a tremendous synthetic fluid with a reasonable price.

Lucas 75/140 Synthetic Gear Oil

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Lucas Oil works excellent for high-performance and heavy-duty applications but not for regular gear lubricants. Here you will get a special additive package that increases the lubricity and insures less gear noise and longer bearing life. Using limited-slip differentials will be a splendid preference when you have Lucas Oil.

If you want your vehicle to stand up even in high temperatures, this oil will help you out. Also, the oil will not let your gear lose its lubricity and works authentically on any engine. It works fine as synthetic oil and holds all capabilities of conventional oil.

Royal Purple Max Gear 75W-140 Synthetic Automotive Gear Oil

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You can use Royal Purple Max Gear for automotive front or rear differentials and trucks. Moreover, it is excellent for manual transmissions and lower gear units that specify an API GL-5 or GL-4 fluid. Soft yellow metals like brass, bronze, copper, and others will remain away from corrosions and will keep your synchronizer safe.

This oil has ultra-tough and high-performance properties, which provides maximum protection to heavily loaded gears. Moreover, it will give complete protection to heavily loaded bags and maximize power throughout the drive train. You will not have to add any extra additives and have a friction modifier as it’s the best feature.

Lucas SAE 75W-140 Synthetic Gear Oil

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Lucas Synthetic Gear Oil is a super slick, long-lasting, and non-foaming lubricant designed for heavy-duty or high-performance applications. The package contains special additives that cushion gear and resists squeezing out under extreme pressure situations.

Maybe you cannot find as good texture as Lucas Oil in other gear lubricants, but that will not be the case in this product. Even your vehicle will not have to lose its lubricity and stand up in high temperatures. Talking about the limited-slip differentials, that can also have great use by this oil.

Valvoline SynPower Full Synthetic Gear OilHas all the properties of performance and ultimate protection projects in both high and low extreme-temperature conditions assists in protecting gear teeth from corrosion and rustReduces chattering from gears
Lucas 75/140 Synthetic Gear OilWorks great for high performance and heavy-duty application additives inside the package increase lubricityFeatures well in limited slipIt stands up in high temperatures Holds all capabilities of a conventional oil
Royal Purple Max Gear 75W-140 Synthetic Automotive Gear OilBest for automotive front or rear differentials work finely in manual transmissions and lower gear units keep the soft yellow metals away from the corrosion Has ultra-tough and high-performance properties It gives maximum protection to heavily loaded gears
Lucas SAE 75W-140 Synthetic Gear OilIt contains a super slick, long-lasting, and non-foaming lubricant The special additives cushion gear and resists against squeezing out It does not let the vehicle lose its lubricity A tremendous handy for limited-slip differentials

75w90: Main Features

FeaturesAdvantages and benefits
It gives resistance to high-temperature oxidation and assures exceptional thermal stabilityExtends bearing life and gear with minimal deposits Has an extended seal life
Owns high torque wear of high-speed scoring and gives protection against low speedConsumes maximum load-carrying capabilities Contributes to reducing maintenance costs with longer equipment life
Upgraded frictional properties Helps in minimizing operational costs
Remarkable low-temperature fluidity and mineral oils Eases in start-up and contributes to reducing wear
It gives good resistance to foaming Ensures reliable lubrication maintaining the film strength

What is 75w90 oil used for

75w90 oils have outstanding anti-wear, anti-weld, and anti-scuff properties. As a result, they can give exceptional bearing and gear protection. Sometimes, lubrication foaming and aeration causes wear, which is prone to damage gears.

Furthermore, we get to see rust and corrosion hampering the vehicles on a high note. To prevent those unpopular substances, 75w90 works excellent. You can use it for railway gearboxes to get an excellent load-carrying capability where we expect shock loading.

75w90: is used in for which cars

The primary purpose of using 75w90 is to enhance the performance of the manual transmission. Hence, the grade gearbox can run thrillingly throughout the route. You can also use it for passenger cars and trucks without having any complications.

Kinematic viscosity[mm2/s]: 115 @ 40° C and 15.2 @ 100° C

Viscosity Index: 138

Low Shear Rate Viscosity: 4.4

High Shear Rate Viscosity:

Temperature Range: 300 °F to 350 °F

Density[g/cm3]: 878 kg/m3

Price range: $29


Oil Flow: Flows well in cold

75w140 Main features

FeaturesAdvantages and benefits
Gives resistance against high-temperature oxidation with exceptional thermal stabilityEnsures long gear and bearing life with minimal deposits Has longer seal life
Outstanding protection against high-speed scoring, high torque wear, low speed Has maximum load-carrying capabilities Reduces maintenance cost with long equipment life
Splendid shear stabilityRetains viscosity under severe operating conditions Includes film strength and prevents wear
Exceptional mineral oils versus low-temperature fluidityEases start-up and reduces wear
It gives a good resistance against foaming Maintains reliable lubrication with film strength
Compatible with typical gaskets and automotive sealsReduces contamination with minimum leakage

What is 75w140 oil used for

The best usage you can ever have of 75w140 is for motorhome / RV, truck and rear differentials, or automotive front. Moreover, you can use it for lower gear units of marine engines and manual transmissions. Other than that, high speed/low torque and high speed/shock load, including hypoid and worm gears operating, are a significant recommendation of 75w140.

75w140 is used in for which cars

Oils like 75w140 are famous for light trucks like Ford Mustang and passenger cars. Other vehicles like Sequoia, Jeep Cherokee, Ford F-150, Dodge Ram, and Toyota Tundra require such oils.

Kinematic viscosity[mm2/s]: 172.4 @ 40° C and 24.5 @ 100° C

Viscosity Index: 174

Low Shear Rate Viscosity: 4.4

High Shear Rate Viscosity:

Temperature Range: -40° F and above

Density[g/cm3]: 869 kg/m3

Price: $21.95


Oil Flow: Can’t flow well in cold

Which oil is thicker, 75w90 or 75w140?

The main difference between 75w90 oil and 75w140 oil is the operating temperature. But on the contrary side, 75w140 oils are thicker than 75w90 oils. But when you keep them a room temperature, they both will own the same viscosity regarding 75w90 vs. 75w140 fuel consumption ratio.

Which oil is better, 75w90 or 75w140?

75w90 oils are comparably thinner than 75w140 oils in higher oil temperatures. But when both are in a lower temperature situation, you will not find any difference. Most of the engine drivers prefer 75w140 for having a more comprehensive viscosity range.

On the other hand, contemplating 75w90 vs. 75w140, which is thicker, 75w140 is more on that side. Ultimately, it will be better if you choose 70w90 for rear and standard duty.

What does 75w90 gear oil mean?

The theme of 75w90 stands for SAE class which is a must-have characteristic for transmission oils. Society of Automotive Engineers makes the classification of it in resuming of multigrade oil.

When you judge on 75w90 vs. 75w140 gear oil, 75w90 lubricates fast and works well at all everyday duty applications.

Properties and specifications of 75w90 oil

Grade: SAE 75W-90

Density @ 15 C, g/cm3, ASTM D4052: 0.86

Flash Point, Cleveland Open Cup, °C, ASTM D92: 210

Kinematic Viscosity @ 100 C, %, ASTM D445: 15.7

Kinematic Viscosity @ 40 C, mm2/s, ASTM D445: 115

Pour Point, °C, ASTM D97: -45

Viscosity Index, ASTM D2270: 144

What does 75w140 gear oil mean?

75W140 presents the SAE class, which makes another must-have characteristic of transmission oils. While gaining a prerequisite knowledge of 75w90 vs. 75w140 oil consumption, 75w140 stands out in heavy-duty applications.

Properties and specifications of 75w140

Grade: SAE 75W-140

Density @ 15 C, g/cm3, ASTM D4052: 0.89

Flash Point, Cleveland Open Cup, °C, ASTM D92: 203

Kinematic Viscosity @ 100 C, mm2/s, ASTM D445: 25

Kinematic Viscosity @ 40 C, mm2/s, ASTM D445: 182

Pour Point, °C, ASTM D97: -45

Viscosity Index, ASTM D2270: 170

75w90 Or 75w140 which one is better?

When it’s about 75w-90 vs. 75w-140 synthetic, 75w90 has just got you covered. But on severe service adoption, 75w140 is nowhere behind. Again, you may think about 75w90 vs. 75w140 towing, where 75w140 emerges more because of its thickness. We may want fast lubrication with regular duty on the flipping side, which marks out for 75w90 oils.

Through continuous use, rear diff and heavy towing are rare options, and you should not go for that much richer. And there is nothing new in the occasional pulling of gears in the front and standard duty. To exemplify that, 75w90 is a better choice you can have.

Can you use 75W140 instead of 75W90?

After many testifications and experiments, we learned that 75w90 oils and 75w140 oils are different from each other. Usually, the manufacturers recommend 75w90 when you are looking for regular duty and fast lubrication. Be it in cold temperatures or hot temperatures, and you will get a former performance in your gear with this oil.

On the other hand, 75w140 contrives the opposite of it. When we want a cumbersome duty application, 75w140 conquers that part. So it will not be relevant if you use 75w140 instead of 75w90 as both the oils are far away from each other.

The viscosity of an oil refers to the weight of Oil. As a result, you can know how well the Oil flows in particular temperatures. If you see, a 5w20 oil flows faster than a 5w30 oil because 20 and 30 in the above indicate the weight of Oil. 

What happens if I use 15W40 instead of 5w30?

Difference between 0W-40 and 5W-40

Will Synthetic Oil Quite Noisy Lifters

Check Difference Between 5w30 and 5w40. And

Check can I use 5w40 instead of 15w40?

What Is Dexos Oil

Buying Guide for a perfect gear oil

You may find it a troublesome aspect while choosing the perfect gear oil. But when the situation arises from f350 75w90 vs. 75w140, then the preference becomes more difficult.

But don’t worry, that will not be complex anymore if you get the proper knowledge with guidance. Yes, you are thinking right. Here, I will show you how you can choose the perfect gear oil for your vehicle.


Make sure you choose an appropriate viscosity grade that recommends simple findings in a component’s maintenance manual. But remember, the manual always does not exist, or maybe the machine can operate outside the conditions.

So, if you don’t justify the methods of viscosity selection, you may miss out on a chance of having a genuine oil.

Selection of additives and gear lubricant

After you select the viscosity grade, make sure you choose the primary type of lubricant. You will get many variations in gear lubricants, like- anti-scuff, R & O, and compounds.

The gear lubricant type should fit the best on the applications, which determines the operating conditions. As there are no standard guidelines to help in determination, selection can be your best venture.

Type of lubricants

Rust and oxidation gear lubricants have no anti-scuff additives and lubricity agents. Some surfaces operate under elastohydrodynamic or hydrodynamic lubrication conditions. Such need lubricants like R & O.

On the other hand, Motul 75w90 vs. 75w140 confines anti-scuff lubricants of extreme pressure. Here the EP additives have sulfur phosphorus which allows chemically active compounds to prevent adhesive wear.

The compound gear lubricants contain synthetic fatty acids to increase lubricity and film strength.

Base oil selection

In most applications, high-quality mineral base oils work fine as they have higher pressure-viscosity than common synthetics. These mineral-based oils allow a more remarkable film of thickness in operating thickness.

Make sure the terms like 75w90 vs. 75w140 jeep and 75w90 vs. 75w140 BMW conservation suits well according to your preference.

Frequently Asked Questions

Which is better, 75w90 or 75w140?

75w140 oils are heavier if you compare with 75w90 but not a bad option if you are looking for severe service. Moreover, for rear diff, heavy towing, and continuous use, 75w140 is preferable. But, it nonetheless will be annoying if you go for heavier oil.

Instead, I will recommend you to use 75w90 for a standard duty while having fast lubrication. And if you are thinking of occasional towing, then 75w90 will hold no grudges on that as well.

Can you mix 75w90 and 75w140?

The ideal quarts you will need are 3.7, which is a convenient one for rear diff fluid. So, even if you mix 75w90 with 75w140, I don’t think that will create any kind of predictable reaction. If you want, you can keep both the oils mixing to your gearbox alone and don’t have to worry about contamination.

Since we know 75w140 is a bit heavier than 75w90, so your oil lubrication may become faster at that time.

Is 75w90 suitable for diesel engines?

75w90 is a fully synthetic gear oil of lubricant formation which comes from synthetic base oils. Also, the advanced additive system makes it possible to work equivalently on diesel engines.

Sources like railway gearboxes will be beneficial with the 75w90 oil and provide excellent capabilities in load-carrying. So, if you expect extreme pressures or shock loading, then you must have a look at this oil.

Which is better, 75w140 or 80w90?

75w140 oils are made for heavy-duty applications like towing. But if you are thinking of trying it on any other application, even that will not be a problem. While on the flipping side, 80w90 are thinner than 17w140, which lubricates fast and saves time.

Moreover, it has extra high-performance giving a selective base to commercial gear oils. So it won’t be an extracting thing if we say 80w90 oil is better than 75w140 oil, especially in lubrication.

What temperature is suitable for 75w140 good?

In a flashpoint, 75w140 oils are suitable to be at 220° C, whereas in a fire point, the ideal temperature of this oil shall be 242° C. Now coming to the pour point, the weather should be less in this situation.

If the oil remains at -43°, that can be an exact condition it can have at that time. While talking about the viscosity of 75w40, it remains at 25 in 100° C and 182 at 40° C.

Is 75w90 good for summer?

We know 75w90 is a fully synthetic gear lubricant with an advanced additive system. You can use it on railway gearboxes and get excellent load-carrying capabilities.

Moreover, we expect extreme pressure and shock loading, which are inevitable in a 75w90 oil. So even if you use it in summer, that will not create any hindrance in the functioning of your gear.

Is full synthetic oil 100% synthetic?

Synthetic oil has artificial chemical compounds and human-made lubricants. Moreover, it consists of chemically modified materials like- petroleum components. But the base materials constantly adapt with distilled crude oil and highly refined petroleum.

And you will not have any grudges on performance because of the API-type standards. Similarly, the synthetic additives will make your oil flow smooth and lubricating. Thus, we can say that such bases make a synthetic oil 100% synthetic.

Does Hyundai recommend synthetic oil?

Hyundai recommends 2020 Hyundai Sonata Oil which needs to be changed every 3000 to 5000 miles when it is conventional oil. But for synthetic oil, make sure to change it ordinarily every 7,500 to 10,000 miles.

Elsewhere, Hyundai recommends traditional motor oil and synthetic blend motor oil, including Quaker State Defy Synthetic Blend. So we can say that ultimately, Hyundai recommends synthetic oil to thrive an outstanding performance in the engine.

When should I use 75w140 oil?

75w140 oil is suitable for HD applications, like towing. But if you require to use it on other applications, even that will be okay and will not create any contamination.

Synthetic oils are more expensive compared to conventional oils, but no doubt in their performance. If you want to give a better resolution to your engine, then you must use the 75w140 oil. But keep in mind the budget as well.

What is the best 75w140 oil to use?

Here are some of the 75w140 synthetic gear oils you can have-

  • Ford Genuine Fluid XY-75W140-QL SAE 75W-140 – Synthetic Gear Lube
  • Valvoline SynPower SAE 75W-140 – Synthetic Gear Lube
  • Royal Purple ROY01301 MAX GEAR 75W140 – Gear Oil
  • Amsoil Severe Gear SAE 75W140 – Synthetic Gear Oil
  • Mobil 1 102490 75W-140 – Synthetic Gear Lube
  • Red Line 57915 75W140 GL-5 – Gear Oil
  • Lucas 10122 75/140 – Synthetic Gear Oil

What happens if you use 75w140 instead of 75w90?

75w140 is a heavy option that is good for severe service. Properties like rear diff, serious towing, and continuous use require a handy like 75w140. But what I think is, you should not go heavier than 75w90 for regular duty because 75w140 contains a thick texture, whereas 75w90 is too thin.

And if you want fast lubrication and quick flow, then using 75w140 instead of 75w90 will not be relevant.

Can I put 75w140 in my petrol car?

Yes, you can put 75w140 oil in your petrol car as it works excellent for transmissions, manual gearboxes, differentials, transaxles, and others. There will be no hassle if you use this oil for communications and want to run it smoothly. Also, the critical internal components will remain safe with the 75w140 oil. So if you’re going to use it in your petrol car, then go ahead.

Can you put 75w140 in a 80w90 engine?

Of course, you can put 75w140 in a 80w90 engine. Both oils work almost the same as synthetic gear oil. Heavy-duty applications, such as towing, requires thicker oil like 75w140. But remember, 75w140 is more expensive than 80w90.

Unless you can’t have an 80w90 oil, you should not try the other one. Though 75w140 oil will not cause any damage to the 80w90 engine, it is better always to use the exact one.

Is 75w140 oil only for diesel engines?

No, 75w140 oil is not only for diesel engines; you can also use it for gearboxes and manual transmissions. If your machine has a heavy-duty drive train that requires lubricants, then 75w140 is just for you. High-performance cars, older vehicles, pickups, and others work great with this oil.

So, whether you have a diesel engine or a gasoline engine, 75w140 oil will make sure about the efficiency of your machine.

Do diesel oils damage gas engines?

Diesel oil contains higher engine temperatures where the oxidation rate, sulfur deposits, fuel soot, and other deposits are high. You will not find such kind of conditions in automobile engines and the reason is diesel engines fail in a critical area.

Most apart, when you will try it on gasoline engines, the expected result may not appear to you. But it is nowhere relevant that diesel oil damages gas engines.

Will 75w140 hurt a 80w90 engine?

No, there is nothing like 75w40 oils will hurt 80w90 engines. Generally, we use 80w90 oil for a 80w90 engine. But when it is about a different oil preference for another machine, that might sound a little tricky.

But don’t worry, the effectiveness of 75w140 and 80w90 are almost the same. So, even if you use a 70w140 oil in a 80w90 engine, it will not create any hindrance; instead, it regularly works well.

What oil is thicker, 80w90 or 75w90?

SAE 75W-90 oils have a consistent viscosity or thickness, which comes across in a wide temperature range. When exposing the oil to high heat, you will see it come out to be thicker.

But when you do the same thing during winter, you will see the oil appear thin because of the wintery conditions.

As with 80w90, the case is not the same here. It remains in higher viscosity and consumes thicker consistency in all seasons.

Wrapping Up

Hopefully, you got your answer of better choice in a juxtaposition of 75w90 vs. 75w140. Both the oils identically comprise merits and flaws. If 75w90 lacks in heavy-duty applications, 75w140 lacks on that part. In the same way, 75w140 lacks in typical duty applications, and 75w90 accomplishes them.

The main comparison you will find here is the thickness. 75w140 is highly thicker than 75w90 and contains more viscosity. Whereas 75w90 is entirely on its flipping side. It lubricates fast, maintains evenly in extraordinary situations, and best for occasional use.

As a consequence, I will tell 75w90 owns the crown against 75w140. That is because this oil supports finer in all possible ways and gains tiny faults which we can rarely see.

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