15w40 vs 10w30: Which assures excellent protection at High Mileage

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One of the most controversial matters we seem to transpire is about 15w40 vs. 10w30 engine oils. But there is nothing to have confusion about if you know all the exemplary aspects. Whenever we go for a purchase of engine oils, the first thing that comes to our mind is if the oil will remove sludge. And most importantly, if you will get a thermal breakdown or not.

There is no doubt 15w40 are great oils in conforming viscosity stability. Similarly, 10w30 leaves no stone unturned in providing solid wear protection to engines.

If both the oils are so good, how would it be easy to find the best one? In this regard, I will help you pick out the right one for the best performance of your engine. So let us not waste more time and see what makes these two beasts different from each other.

10w30 vs 15w40: Comparison Table

Kinematic viscosity[mm2/s]15.4 at 100° C and 119 at 40° C11 at 100° C and 69 at 40° C
Viscosity Index135140
Temperature Range-22F to 122F210° F
Density[g/cm3]848.3 kg/m³865 kg/m3
Thickness1.39mPasMore than 1.40mPas
Oil FlowCan’t flow well in coldTakes 30 seconds to flow
Density[g/cm3]872.5 kg/m³865 kg/m3

What happens if I use 15W40 instead of 5w30 let’s find it out.

15w40 Main features

15w40 Main features

Not knowing the features of engine oils makes us take them for granted. On that note, the same goes for the 15w40 oil. Indeed, it shows an integral performance ranging from longevity in all engines to absolute properties.

Minimizes friction and wear

To minimize friction, 15w40 is nonetheless the choosiest one for engine drivers. Also, the wear between components will reduce significantly with a preventive heating system.

The lubricants on metal surfaces will become smooth with the 15w40 and remove all sorts of abrasion.


This motor oil makes sure that no components adhere to each other and suspend contaminants soon. The detergents inside 15w40 oil help to remove dirt and make the engine solvent with additive dispersants. And if any sludge appears in your engine, this oil is going to remove that as well.

Cool engine parts

Considering the 15w40 vs. 10w30 oil consumption, 15w40 lowers the overall temperature of the engine. It also calmly decelerates the heat of moving parts, reducing friction thoroughly. This oil will also absorb the whole heat which has been merging in the contact surfaces.

What is 15w40 oil used for?

For complete success in over-the-road diesel trucks, 15w40 oil is the relevant one. Moreover, you can use it for off-highway diesel equipment, farm tractors, and passenger cars. The backward compatibles are light trucks with diesel, turbo-charged diesel engines, or gasoline engines coming to API oil categories.

Form a seal

15w40 oil functions dynamically in combustion chambers and will work significantly, reducing consumption.

Transfer energy

The lubricants in this oil are incompressible and have an energy transfer medium. So be sure that the oil will work finely, actuating the components as a hydraulic fluid.

Dampen shock

15w40 oils blow mechanical shocks performing like cushions. It absorbs the energy strikes over a broad contact area and disperses them slowly. There is a vital lubricant in this oil that resists rupture and reduces the opposing forces.

Specification of 15w40

Kinematic viscosity[mm2/s] :15 at 100 °C and 11 at 40 °C

Viscosity Index: 143

Low Shear Rate Viscosity: 12.5 to 16.3 mm2/s at 100g

High Shear Rate Viscosity : 3.5 at 150g

Temperature Range : -22F to 122F

Density[g/cm3] : 872.5 kg/m³

Price : $155.45

Thickness : 1.39mPas

Oil Flow : Not so cold

15w40 is used in for which cars

Both the oils serve the best if you compare them as 15w40 vs 10w30 high mileage, including the viscosity and thickness. But the situation will not be the same always, especially during the dead of winter.

Don’t worry about the lubrication, and they will work effectively in terms of functioning your engine.

If you have passenger cars, diesel light trucks, turbo-charged diesel engines, gasoline engines, and so on then, 15w40 will be the best choice.

Top 3 best 15w40 oil

#1. Shell Rotella T5 Synthetic Blend

Shell Rotella T5 Synthetic Blend

Shell Rotella T5 Synthetic Blend combines synthetic base oils and advanced additives. Here you will get advanced additives that help to deliver excellent protection. Even in cold weather, this oil flows smoothly and makes sure that your engine remains precise all the time.

Rotella’s Synthetic Blend Technology suits well in a wide range of heavy-duty engine applications. If you want an alternate for on-highway fleets, then this oil will be your perfect choice.

Not only that, you can use it for construction, agriculture, and diesel pick-up trucks, including high-power vehicles.

Where you will need resistance to increased heat and stress, this product will help you out. Going beyond CK-4 wear limits, the oil will demonstrate 55% better deposit control.

Moreover, it will deliver good engine cleanliness and reliability at extended oil drain intervals.

#2. Royal Purple’s API-licensed Motor Oil

Royal Purple’s API-licensed Motor Oil

Royal Purple’s API-licensed Motor Oil combines proprietary additive technologies and premium base oils. It creates a high performance that optimizes engine fluency.

You will get superior protection in your gasoline and diesel engines which will meet warranty requirements. Passenger cars and light trucks will go well in a long route with this oil.

If you are thinking about the metal-to-metal contact, that’s avoidable here. There will be no stress about any particular procedure, as the oil doesn’t require so.

The Royal Purple’s oil is now offering many viscosity grades of API-licensed motor oils.

And guess what? You can run your vehicle efficiently for 8,000 to 10,000 miles because of the effective functioning this oil serves. Improved oxidation and viscosity stability will be your car’s essence once you purchase this product.

#3. Valvoline Premium Blue

Valvoline Premium Blue

Valvoline Premium Blue is endorsed by Cummins and designed to provide modern performance and protection.

Here the equipment involves emissions treatment of diesel engines with Exhaust Gas Recirculation (EGR), Diesel Particulate Filters (DPF), and others.

The One Solution Technology inside is suitable for a wide range of heavy-duty engines.

Diesel gas and natural gas applications will work at their best with this product. Moreover, the oxidation resistance is outstanding, which supports long oil life in heavy-duty engines.

The exclusive design of this oil conveys the professionalism of American-made heavy-duty diesel trucks. You will surely get resistant support for its outstanding oxidation, which will provide a long oil life.

Shell Rotella T5 Synthetic Blend Delivers an excellent protection Flows smoothly even in cold weather Best for highway fleetsSuits well in heavy-duty engine applications Gives resistance to increasing heat
Royal Purple’s API-licensed Motor OilCreates high performance and optimizes engine fluencyProvides superior resistance to diesel and gasoline engines Avoids metal-to-metal contactFulfills all warranty requirements Has improved oxidation and viscosity stability
Valvoline Premium BlueProvides modern performance and protectionInvolves emissions treatment of diesel enginesSuitable for heavy-duty engines Has outstanding oxidation and resistant support

10w30 Main features

10w30 oils are nowhere less than 15w40 if you grab its main features. On that note, I am going to show you why this oil performs so well. And why the marketplace is keeping it on their priority.


The engine parts which remain in constant friction will lubricate easily with the help of 10w30 oils. As it reduces friction, the wear and tear will disappear simultaneously from engines.


When friction between the mechanical parts occurs, they raise the temperature and lose energy through combustion. 10w30 oil helps to release heat, conjoining a lubrication circuit and supplements a coolant. And thus, your engine parts will remain good within a cool temperature.


10w30 has a fundamental cleaning power and keeps the microscopic deposits in suspension. Most often, the combustion residue or dust decreases the performance of an engine. 10w30 oil will carry these impurities to the oil filter, where they can be trapped easily.


Who doesn’t want to enhance the sealing of pistons and cylinders in their engines? 10w30 oils do that exactly. They will enhance the engine sealing, ensuring a protective layer between the various layers.

Protection against corrosion

Sometimes our engine gets corrosive acids that damage our engine parts. But when our motor oils supply the additives, they slow down the corrosion. 10w30 also does the same and removes the corrosion inhibiting role.

What is 10w30 oil used for?

To gain complete success in over-the-road diesel trucks, 10w30 oil is the relevant one. Moreover, you can use it for off-highway diesel equipment, farm tractors, and passenger cars. Coming to API oil categories, the backward compatibles are light trucks with diesel, turbo-charged diesel engines, or gasoline engines.

Kinematic viscosity[mm2/s] : 11 at 100° C and 69 at 40° C

Viscosity Index : 140

Low Shear Rate Viscosity :

High Shear Rate Viscosity :

Temperature Range: 210° F

Density[g/cm3] : 865 kg/m3

Price range: $59.99

Oil Flow : Takes 30 seconds to flow

10w30 is used in for which cars

Private vehicles and petrol engines hoe perfectly well with 10w30 motor oils. Moreover, light-duty diesel and other cars with heavy load engines work the best when they have this oil. So if you any one of them, you can choose the 10w30 being ascertained.

Top 4 best 10w30 oil

#1. AmazonBasics High Mileage Motor Oil

AmazonBasics High Mileage Motor Oil

AmazonBasics High Mileage Motor Oil comes up with a fantastic 10w30 engine oil where you will get six packs in 1 quart. Here you will get high rated products at a meager price without any performance inquiry. But before you are going to apply the oil, make sure you have the manufacturer’s recommendation.

Engines over 75000 miles will work conveniently, and for longer drain intervals, it will be up to the mark. Usually, our engines suffer from build-ups which causes rust and corrosion. But that problem will be no more if you have AmazonBasics engine oil.

This oil will undoubtedly reduce frictions and give a high resistance to viscosity and thermal breakdown. And if there are any exhaust emissions, that too will disappear from your engine.

#2. Valvoline Advanced Full Synthetic

Valvoline Advanced Full Synthetic

Valvoline SynPower Full Synthetic Motor Oil fights crucially with heat, deposits, and wear. So stay tension-free about engine protection because here, the anti-wear additives will give durable solutions. And the industry standards assure to stay the oil for a long time.

There are anti-wear additives that provide 50% more wear protection. Moreover, the complete synthetic formula will save your engine while high and low temperatures. You will find extra detergents inside the product that will fight sludge and deposits. And some super antioxidants will resist your motor oil breakdown even in extreme conditions.

#3. Valvoline MaxLife

Valvoline MaxLife

Valvoline MaxLife addresses the unique needs of higher mileage engines. It owns the title of first motor oil specially formulated as a blend of synthetic and premium conventional base stocks.

You will find seal conditioning agents, extra cleaning agents, additional anti-wear additives, and novel friction modifiers here. They give perfect protection to diesel engines.

Undoubtedly, you will get a thick & durable layer of anti-wear film, which prevents auto engine breakdown. Furthermore, the detergents will help to protect against sludge and deposits.

And no leaks will prevail on your engine for the premium seal conditioners. Breakdowns will be far away because of the superior antioxidants the oil has.

#4. Pennzoil Platinum Full Synthetic Motor Oil

Pennzoil Platinum Full Synthetic Motor Oil

This Platinum Full Synthetic Motor Oil is made for excellent performance in extreme temperatures. Pennzoil provides a faster low-temperature oil flow and protects even in extreme heat.

You will get unsurpassed wear protection from friction which is not compromisable at all. The unbeatable engine protection will clear deposits and keep your pistons cleaner than required by the industry standard.

Pennzoil’s products act against loss of power, wear and deposit formation. This 10w30 will flow fast in frigid temperatures and travels quickly to lubricate the various engine parts.

In hot temperatures, it gains a lower tendency to evaporate but ground up with more challenges.

AmazonBasics High Mileage Motor OilEnsures high performance of the engineMakes longer drain intervals up to the markWorks conveniently over 75000 miles Removes build-ups, rusts, and corrosion Reduces friction and gives high resistance to viscosity
Valvoline Advanced Full SyntheticFights against heat, deposits, and wear Gives durable solutions with anti-wear additives Will assure 50% more wear protection Resists breakdown even in extreme conditions
Valvoline MaxLifeGives perfect protection to diesel engines Has a thick and durable layer Prevents auto engine breakdownsProtects against sludge and depositsDoesn’t allow any leaks to merge
Pennzoil Platinum Full Synthetic Motor Oil Provides a faster low-temperature oil flowGives unsurpassed wear protection from friction Clears deposits and pistons precisely Flows fast in freezing temperatures

What does 15W40 engine oil mean?

We know the “w” in 15w40 indicates the winter for engine oils, and 40 means the weight of this oil. In cold temperatures, this oil will thin out into a weight of 15.

You can frequently see that the 15w40 has an HD written on its cover. This HD means heavy-duty, which increases the thickness and viscosity of the oil.

There are modern oil detergents inside the products, which play a crucial role in circulating.

Properties and Specifications of 15W40 oil

  • Grade : SAE 15W-40
  • Density @ 15.6 C, g/ml, ASTM D4052 : 0.866
  • Flash Point, Cleveland Open Cup, °C, ASTM D92: 230
  • Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 : 14.6
  • Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 : 107
  • Ash, Sulfated, mass%, ASTM D874 : 0.5
  • Total Base Number, mgKOH/g, ASTM D2896 : 6
  • Pour Point, °C, ASTM D97 : -39

Advantages and Benefits of 15w40:

Control and Dispersancy

15w40 has a soot dispersancy which assures an excellent range. And additionally, you will get a firm wear control.


This oil gives an extended drain interval protection with fast lubrication. Also, the wear and corrosion will not even touch your engine.


15w40 oils consist of super anti-oxidation characteristics. As such, this oil will remain stable in high temperatures.

Superior formula

In all 15w40 oils, there is a mixture of superior formula which helps to reduce sludge. As a result, all the varnish formation will go away and make your engine versatile.

What does 10W30 engine oil mean?

As I mentioned before, “w” indicates the weight in engine oils, and the 10 in 10w30 means the temperature when it is cold. Again, you may contradict that what the 30 refines here? It means the highest temperature the oil can hold up when the engine becomes hot.

Properties and Specifications of 10W30 oil

  • Grade : SAE 10W-30
  • Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 : 10.4
  • Density @ 15.6 C, g/ml, ASTM D4052 : 0.859
  • Flash Point, Cleveland Open Cup, °C, ASTM D92: 232
  • Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 : 66
  • Pour Point, °C, ASTM D97 : -42

Advantages and Benefits of 10W30 oil

Advanced full synthetic formula

Here the advanced synthetic formula will keep your engine new and run authentically.

Outstanding thermal and oxidation stability

The 10w30 oil will protect your engine up to 10,000 miles between oil changes.

Outstanding low-temperature capabilities

These oils will give fast protection and quick cold-weather starting, which helps to extend the engine life.

Active cleaning agents

The sludge that remains behind the engine will budge away by the complete proof design of 10w30 oils.

Precisely balanced additive component system

With unsurpassed wear protection, you can keep your engine oriented all the time.

15w40 vs 10w30 which one is better [5w40 or 10w30 ]

While comparing 15w40 vs 10w30 hot weather and cold weather condition, 10w30 is thinner than 15w40.

But the firm strength is not always the same if you choose a compromisable quality. So always be alert that you are buying the high-quality one to get the best results.

Contrastingly, 15w40 is nowhere less than 10w30 if you think of the authenticity in your product. As a piece of mere advice, I will suggest you not to go for extreme thick oil.

Because these are prone to oxidation, and so is the 10w30. Though such oils are thinner than 15w40, you must be concerned about viscosity as well.

Every engine driver thrives for a good flow of oil which gives adaptable lubrication. On that note, 10w30 works better than 15w40.

So, if an increased thickness annoys you frequently, 10w30 is the relevant one you can have for maximum use.

Will Synthetic Oil Quite Noisy Lifters

Check Difference Between 5w30 and 5w40.

Buying guide for a perfect engine oil

Engine oils vary in general and specific qualities working to acceptable standards. You may predict a high-quality oil as a poor one or an insufficient quality oil as high-quality.

For this reason, it is imperative to justify all the essential features of pertinent engine oil.

You don’t have to stress about finding the best one if you know all the engine oil needs. Here is a buying guide to help you when you are looking to buy such oil for your engine.


Viscosity means the fluid resistance flow of oil. Here the energy plays a vital role in pulling the molecules apart where several of them are attracted to each other. Thus, the molecules create a large flow and also the viscosity in forming an attraction.

Again, you will require energy to overcome the molecule’s attraction, which will create a fluid flow. Always consider the viscometric behavior and chemical qualities when you go to buy an engine oil. And settle your mind conforming on 15w40 vs 10w30 which is thicker before buying one.

Type of fuel

You must clarify what fuel your vehicle runs before buying oil. Which one can be suitable, diesel, petrol or LPG? After you become 100% sure, you can choose the correct one without any hesitation.

API or ACEA classification

Most importantly, check the oil label, if there is any API or ACEA classification or not. Once you get it, you find a determination of the suitability of your oil in all engines. The standards regularly upgrade with the improvement of technology.


If you are buying engine oil for the first time, then you shall expect a rate of $25 to $50. The 15w40 oils will range from $30 to $60 for 5 liters coaxing on semi-synthetic. And they are pretty expensive compared to other oils.

They will cost around $40 to $90. Again, departing in 15w40 vs 10w30 price comparison, 10w30 will cost less. While making a reasonable price is all that matters, choose your oil according to your price wisely.

Frequently Asked Questions

Can I use 15W40 instead of 10W30?

Yes, you can use 15w40 instead of 10w30 but won’t find that convenient. In cold conditions, it will flow slower but will not make that much difference. When the outside temperature will be above 50° F, the oil will burn less.

But if your motor is not smoking or burning less, it will be best to use 10w30. Similarly, 15w40 can be all you have its suits with your engine.

Can I use 10W 40 instead of 15W40?

With the rise of temperature, viscosity and thickness also increase at the same time. Usually, 10w40 oils are thicker than 15w40 in cool conditions but acquire the same viscosity in high temperatures. And the viscosity number of this oil dictates cold start performance in winter. Consequently, 10w40 will work better in times of cold starts if you compare with 15w40.

What is 15W 40 oil used for?

15w40 is heavy-duty engine oil that you can use for complete success in over-the-road diesel trucks. Moreover, off-highway diesel equipment, farm tractors, and passenger cars are pretty reliable on 15w40 oil.

Or you can also use it on light trucks with diesel, turbo-charged diesel engines, or gasoline engines. And the previous API Oil Categories are more compatible backwardly. Undoubtedly, you can have a wide range of performance using 15w40 oil.

Is 15W40 oil thicker than 30 weight?

The local dealers recommend using 30 weight for an efficient result of engines. And there will be no hassle to put everything on 15W40 oil. Tractors like 5488 go well with this oil. But when you talk about thickness, 15w40 is the one that consumes high viscosity, mainly during the winter. Also, the 1460 combine can hold a thickness of 15w40. So it’s inevitable that 15w40 oils are thicker than 30 weight.

What 15w40 means?

15w40 is a multi-weight oil having a precise viscosity grade. In 15w40, 15w means a cold grade of 15, whereas 40 means the viscosity grade of 15w in running temperatures.

Here the viscosity drops, and oil becomes thin. If the viscosity grade is higher, you have to understand that the thickness is also higher.

Such kinds of viscosity affect heat capacity, lubrication, and flow. Therefore, 15w40 will have the same viscosity as a 40 grade.

What is SAE 30 oil?

SAE 30 engine oils are of high quality which acts like age-resistant mineral oil. You will also find an excellent viscosity-temperature behavior where it raffinates.

The manufacturers add additives depending on the applications.

Materials like unalloyed are offered for SAE 30 oils while structuring classic cars. You can use this oil in small engines; it serves a non-detergent texture. Again, the 30 in its name describes the rating of viscosity.

What is 10w30 oil used for?

10w30 is an ideal oil for heavy load engines as it owns all the abilities to withstand hot temperatures. You don’t have to compromise your engine performance even due to its multi-grade features.

The viscosity grade of 10w30 is 10 when put in cold temperatures. And when your engine is at high temperature, the viscosity grade this oil will serve is 30.

It is a remarkably thinner oil, so you won’t get any difficulties in flowing and moving.

What’s better 5W30 or 10w30?

If you consider from the side of lubrication, 5w30 is better than 10w30. Light duty gallons of diesel, petrol engines, and other private vehicles suit best with 5w30 oil.

On the other hand, 10w30 oils are suitable for commercial vehicles. Especially the heavy load engines and passenger cars will be helpful from this oil.

Moreover, 10w30 is thicker than 5w30 and provides a better sealing capability. But it can flow as smooth as 5w30 does.

Which oil is better 10w30 or 10W40?

Both the oils, 10w30 and 10w40, holds a temperature difference, which is the high-temperature viscosity. 10w40 is relatively thicker than 10w30 in high temperatures, and 10w30 moves are quickly comparing to it.

But make sure you are always using the correct viscosity. It will help to reduce friction, ease starts, and slow wear.

But for a smoother flow, 10w30 does a great job. Though 10w40 is efficient in warmer temperatures, but can’t lubricate as fine as 10w30.

Is it OK to put 10W40 in a 10w30?

Many of the manufacturers say that you can mix 10w40 and 10w30 if you live in warm temperatures. Therefore, your engine will have no problems even if you put these two oils together. Also, if you want, you can put synthetic, conventional blends, and other motor oils.

But not all laboratories dignify it as a proper option though no harm is still found in vehicles by the two oil’s mixture.


From the core points of 15w40 vs. 10w30, I hope you found your choosiest product. What type of thickness, viscosity, or stability you want matters solely when you are up for an engine oil acquisition. When you find faults in 10w30, you get that feature as a champion in 15w40, and the same goes for the other.

Nonetheless, being unsure about anything, we have to weigh which oil carries our requirements most. Pointing on that part, I will be recommending you the 10w30 but of a high-quality one. Because they flow easily, lubricates quickly, and perform precisely. So, what about giving it a second thought?

Chad Christiansen

Hi, I am Chad Christiansen the chief editor and fuel expert share tips to extend the life of your car Engine. I am expert in additives and product specialist in Synthetic, Gear oil, Diesel, Gasoline. Connect me

This Post Has 2 Comments

  1. Christo Dorfling

    Good day

    I am driving a Toyota Fortuner. The dealer filled it with 10W30.

    The 200 thousand km service was done by a new person, and they filled it with Fuchs TOTAN 15W40 engine oil.

    I am only driving long distances, and the current temperature in South Africa is above 20 degrees Celsius.

    Was it the best decision?


    Christo Dorfling
    Pretoria, South Africa

    1. Chad Christiansen

      10W-30 is thinner than 15W-40 oil, its film strength can be weaker and it can be more prone to oxidation.So Stick with 10W-30 oils that can perform as well,

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