Difference between 5w40 and 10w40 engine oil

10w40 vs 5w40 Oil

10w40 vs 5w40 Motor Oil

Many motorists when choosing an engine oil for winter or all-season use often choose between 5w40 and 10w40. These are the most popular oil grades for European cars. For Asian and American cars, it is common to use 5w30 or 10w30 viscosity oil. To understand which is better, it is necessary to compare the performance characteristics of these fluids and determine what the differences are.

Only after that, it will be possible to conclude what is more suitable for your car, the climate in the region, and operating conditions. We will tell you how 5w40 and 10w40 may differ.

The difference between 5w40 and 10w40 engine oil

Quick answer:

5w40 viscosity motor oil is most often synthetic has a higher flow and is used for low mileage vehicles. 10w40 is a thicker oil and is most often used for higher mileage vehicles.

And now for more details.

Choice of engine oil 5w40 and 10w40

The quality of the engine oil used in the internal combustion engine is not the only factor that determines the total service life of the unit. By minimizing the friction between the metal parts you can achieve better power, lower noise, and vibrations, and lower fuel consumption.

Choosing a good engine oil, which will fully meet the technical specifications, is usually not very difficult. It is more difficult to differentiate between the different types of lubricants, which have letter and number designations.

What is the difference between 5w-40 and 10w-40 oil?

Quite often the manufacturer of the car recommends using 5w40, whereas the sellers of the oil insist on the higher efficiency of using 10w40 motor oils.

How to pick up the right oil for your car and if it is possible to mix different viscosities of lubricants will be discussed in detail below.

All engine oils should be divided into summer, winter, and multigrade.

To understand the difference between these lubricants it is necessary to get acquainted with the deciphering of digital and letter designations:

  • Summer – the marking consists of the numbers: 20, 30, 40.
  • Winter – the designation includes the letter “W”.
  • All-season – the designation includes the letter “W” and the numbers on the right.


The numbers to the left of the letter “W” indicate the lower air temperature limit at which the vehicle can be operated. The figures to the left of the letter “W” indicate the lower limit of the air temperature at which the vehicle can be operated. Figures to the right of the letter indicate the maximum possible positive air temperature at which the lubricant can be used without loss of performance.

  • A value of “5” indicates the vehicle can be driven at air temperatures as low as -30°C / -22°F.
  • A value of “10” indicates that the vehicle can be driven down to -25°C / -13°F.


The difference is small, but using an oil that does not match your vehicle’s actual operating conditions can cause serious deviations in the performance of your vehicle’s powertrain.

  • The “40” number for a 5w-40 and 10w-40 oil indicates the ability to operate your vehicle at ambient air temperatures not exceeding 40°C / 104°F.

From the above specifications, it is obvious that 10w40 oil is thicker than 5w40.

As you know, the higher the viscosity of the lubricant, the higher the air temperature you can use it at. This rule is also true for negative values, so the density of 5w40 oil will be noticeably lower in comparison with 10w 40. Accordingly, if you want to know which oil is greasier, you can again compare the minimum operating temperature to the density of the lubricant.

What grade should I choose: 5w-40 or 10w-40?

First of all, the right choice of lubricant depends on the minimum air temperatures in winter, but only this selection criterion should not be limited when

  1. Operating a car with high mileage.
  2. When changing oil more than once a year.

If the car has been operated for many years and the engine has not been overhauled, the resource of the unit will be positively affected by the year-round use of 10w40 oil.

This type of lubricant is denser, so even in the presence of significant clearances will be observed a lower level of engine vibration, which will certainly have a positive impact on the durability of the work.

If the car is new, even in this case you should know what oil is best for the operation. The optimal option when trying to solve the question of what oil for the summer is 5w40 or 10w 40 to use, the unequivocal answer is 5w40.

In the engine of a new car, all the clearances are completely normal, so you can not be afraid to operate this type of lubricant in the summer and throughout the winter.

Technical information on 5w40 oil

Motor oil 5w40 has the following main characteristics:

  • Class – synthetic oil
  • Engine type by duty cycle – four-stroke
  • Types of engines – gasoline, diesel, turbocharged
  • Purpose – for cars

Engine lubricant labeled 5w40 has these established properties:

  • At 100° the kinematic viscosity is in the range of 12.5-16.3 mm2;
  • The turnover rate at -30° does not exceed 6600 mPa-s;
  • The pumpability at -35° does not exceed 60,000 mPa-s;
  • At 150°, viscosity and shear rate tests give results no lower than 2.9 mPa-s.

The 5w40 oil is formulated to maintain performance over extended service intervals. The use of this product increases the service life of the engine. It does not get “dirty” with oil and does not require regular flushing.

The substance 5w40 has low volatility and ignition temperature in the open crucible method. Because of this, negative deposits are reduced and oil burnout is reduced. 5w40 does not destroy engine sealing elements.

Technical information on 10w40 oil

The substance 10w 40 belongs to the group of conventional oils. Such products are formed by adding various synthetic additives to the mineral base. As a result, many indicators of mineral oils are improved, and a cheaper version is produced in comparison with synthetic. The 10w-40 motor oil, which is considered an all-season oil, belongs to the golden mean.

A 10w-40 engine lubricant has a number of advantages:

  • Unique viscosity values
  • Extended service life without quality loss
  • Wide temperature range

10w-40 engine oil is the most popular product in the European market, in the American market 10w-30 viscosity oil is more popular. You need to try to choose the best option in the ratio of cost and stated quality.

Synthetic 5w40 oil is more liquid compared to semi-synthetic 10w 40. This means that in the heat of the lubricant 5w40 will have to add thickening additives. And here already there can be additional difficulties with the correspondence to the concrete modification of the engine. Therefore 10w 40 is better to use in hotter climates.

Although less viscous, 5w40 synthetic is more stable and resistant to chemical changes. It provides a high level of protection of engine parts against wear and tear. Synthetic oil is best suited for new engines. For example, many manufacturers recommend using 5w30 at the initial stages of car operation. Such substance may also be suitable for engines with average mileage.

An oil 10w 40 is better for engines with higher wear. It has a higher viscosity. This quality will help to seal the formed gaps between parts of the piston group and other engine units. The 10w 40 greases will better protect a worn engine from further loss of power.

The difference between 5w40 and 10w 40 oils is not so much due to the lower temperature parameters, as to their belonging to different types. The same viscosity values in practice are corrected by the synthetic and semi-synthetic nature of each of these products. It should not be forgotten that the difference in price will be tangible. Synthetic products belong to the most expensive because of production difficulties.

Consideration of automobile parameters

When choosing lubricants, you can be guided by recommendations from manufacturers of specific car models. However, during the operation of the car, specific indicators that should be taken into account become more important.

Basic vehicle parameters:

  • Engine year
  • Operating conditions: moderate and severe
  • Engine wear
  • What kind of oil was previously used?
  • Compatibility of old and new oil

Selection of oil depending on mileage

If the service life of the engine has exceeded 150,000 miles, it is necessary to refrain from using additives. In such cases, engine cleaning additives with a strong effect may be particularly dangerous. It is better to use anti-seize additives. This way it is easier to keep the performance of the engine, which has not yet undergone an overhaul or quality preventive maintenance.

You should not ignore the listed engine parameters. On the contrary, taking them into account, it is much easier to choose a suitable lubricating option. The product line 5w40, 5w30, 10w30, 10w40 allows you to meet the basic requirements for comfortable engine operation in various conditions.

The modern market offers a huge number of engine fluids in different ranges. An oil that has attractive indicators on one scale, can be disappointing on other parameters. The popularity of 5w40, 5w30, 10w30, and 10w40 engine oils is proven by their performance and adaptability to the vagaries of the weather. The final choice of one or another product depends on the individual consumer and the anticipated driving conditions.

What brand of oil to choose?

We recommend using engine oil of popular brands, such as:

  • Castrol
  • Mobil
  • Motul
  • Liqui Moly
  • Shell
  • Amsoil
  • RedLine
  • Valvoline
  • Pennzoil

What else do I need to know?

When using all-season oils, regardless of the labeling, you need to be aware of the basic rules for changing lubricants. It is recommended not to change engine fluid manufacturers too often. Even with the same oil density, the products of different firms have significant differences in composition.

If the car has been driven for a short time and the mileage covered is not enough to change the oil, the question may arise whether it is possible to add 10w 40 to 5w40 after the winter period of using the car.

If the 5w40 oil level drops significantly, it is recommended to refill with 10w40 made by the same brand. Otherwise, in spite of the oil belonging to the same class, the interaction of additives included in different lubricants may be incorrect.

If this method of increasing the oil level is a temporary measure, there may be no serious consequences for the engine. If you use a mixture of different liquids for a long time, there can be significant wear on the engine parts. Especially the crank pins and piston group, which are constantly exposed to high loads during operation, may suffer greatly.

Tips and recommendations

When selecting lubricants, observe the recommendations of the vehicle manufacturer. Deviations from the rules are only possible with significant mileage. In that case, thicker oil can be used to provide sufficient pressure in the lube system for increased clearances.

If the mileage is more than 120,000, you should use a 10w-40 product with special anti-seize additives. In this case, it is possible to achieve partial restoration of worn-out parts and significantly increase the engine life.

If necessary, oil of other viscosity and oil types may be added up to 15 % of the total volume.

Regardless of the oil belonging to different temperature conditions, the use of counterfeit products will definitely lead to significant engine wear and fuel overruns.


Now you know the difference between 5w40 and 10w40 oil. If the lubricant change is done correctly, the transition from one type to the other will be almost unnoticeable.

My friends and I created this site to tell you a lot of useful things from the world of cars. I worked as a salesman in a big auto parts store and gained a lot of experience in this field, now I am sharing my experience with you.

Rate author
auto mechanic guide