Choosing between synthetic and semi-synthetic motor oil SAE 10W-40

Car enthusiasts who come to a car service center for maintenance often hear from the mechanic that 15W40 engine oil has very good characteristics. Compositions with such viscosity are mainly used by residents of regions with warm or temperate climates.

When purchasing it for servicing used cars, the total mileage must be taken into account. Severely worn engines require a lubricant with increased viscosity that reliably protects parts operating at high temperatures. The properties of 15W 40 engine oil fully meet these requirements.

General characteristics

Semi-synthetic oil is obtained by mixing 70-80% mineral and 20-30% synthetic base oil, plus additives. Semi-synthetics have good fluid characteristics at an affordable price and ensure reliable engine operation.

Marking 10w - 40 according to SAE (international oil classification system) means the following.

1. 10 w - winter motor oil. It is used at temperatures down to -250C, the letter w is winter.
2. 40 indicates the maximum temperature for normal operation of semi-synthetics - +40 0C.
3. 10w means the cranking temperature is -20°C,
4. Pumpability when marked 10w occurs at a critical temperature of -30 °C

The specified oil is all-season, the application temperature range is -25…+35 0С. Using this semi-synthetic at a higher temperature will reduce the density of the liquid, and at a lower temperature the oil will become very thick (the engine will not start).

10w - 40 can be used for old engines and for new generation engines, its technical indicators will remain unchanged. This product is most often used for power units with high mileage.

Relationship between density and viscosity

When choosing oil for his vehicle, the driver is guided by the SAE classification, which characterizes the liquid by viscosity index. There is no separate classification based on density. In our climate, all-season products are relevant.

So, the letter W in the marking means winter lubricant. Winter oils have a range from 5W to 25W. At a value of 5W, the product does not lose its performance down to -30C, and at 20W the lubricant is effective only in mild frosts. Summer lubricants have low viscosity. Their markings range from 10 to 60.

Product evaluation method

There are two known ways to evaluate motor oils:

• laboratory analysis, plus bench tests;
• study of API classification.

Convenient second method: eliminates the need for testing and does not harm the power unit. By looking at the oil quality indices set by API employees, you can choose the best. This method is designed for engine fluid to operate under ideal conditions. Its results on our roads are questionable.

For laboratory analysis, select independent laboratories, preferably 3, with state accreditation. The first task we set is to determine the effect of automobile oil on the power, toxicity, and efficiency of a particular engine. Of course, testing for all liquid samples will be carried out under the same conditions on the same engine, with the same gasoline.

For other laboratories, we will give for research the motor oil obtained after testing by the first laboratory. We are not interested in the characteristics of fresh motor fluid from a canister, but in the performance of the oil drained from the engine after the test. Because the indicators of the liquid that entered the engine, heated up to 200 0C, reacted with oxidation products and worked for 12 hours will indicate the real life of the oil. Using the method of research and analysis, we will determine the physical, chemical and tribological characteristics of oils. As a standard with which we will compare all liquids, we will take the test results of non-competition automobile oil - cheap mineral oil with a viscosity index of 10w - 40.

"Lukoil" 15W40

The product from Lukoil with this viscosity is a fairly high-quality liquid, and it is made on a mineral basis. Its use is appropriate on forced engines that run on diesel or gasoline, but do not have turbocharging. Also used on cars, trucks and buses.

Pros:

1. No oxidative reactions.
2. There is no carbon deposits in the engine.

Automotive and ZMZ approve the use of this oil.

Nomination: influence of engine mixture on fuel consumption

Averaged fuel consumption data for all modes of vehicle operation determined the winner among semi-synthetic motor oils 10w - 40. The leader was the product with the lowest fuel consumption relative to the base oil consumed. The winners are brands ZIC, Shell, Esso. They are 8% more economical than simple mineral water.

How did you get the percentage of dimensions with the same viscosity index? It's simple: kinematic viscosity was determined in capillary viscometers not at a temperature of 100 0C (specified by GOST 33), but at a temperature of 200 0C (arising in the friction units of the engine during its operation).

There is an optimal viscosity value at which the engine operates well without consuming excess fuel. Indicators less than optimal ensure an increase in gasoline consumption. The brand with the nominal viscosity is Mobil.

Shell Rimula 15W40

There are 2 types of lubricant from this manufacturer and with the specified viscosity: Shell Rimula R4 L and Shell Rimula R4 X. They differ in the specifications and tolerances of the automakers. Both products are actively used in cars of domestic and European brands, are highly compatible with exhaust gas purification systems, and their use reduces engine maintenance costs. If you believe the reviews, Shell Rimula products are fairly high-quality oils, but there are often fakes on the market, so when choosing, you need to pay attention to the canister.

However, it is quite difficult to distinguish a fake today. Fraudsters have learned not only to counterfeit packaging, but also the product itself. As a result, many drivers use counterfeit oil without even knowing it. That is, there are no signs of poor quality at all, and the engine feels great.

Nomination: engine power and dynamics, cleaning properties

Participating semi-synthetic brands showed identical results when testing the specified parameters, with the largest difference being 1.5%.

Motor fluid creates a protective film in friction units, the thickness of which depends on the viscosity of the oil. An increase in viscosity delays the threshold of film destruction under load, increasing the friction force, which leads to a decrease in the power of the power unit. Engine mixtures with low viscosity increase power due to reduced friction. But there comes a time when the oil film is completely destroyed - this leads to a major overhaul of the engine.

The cleaning properties of all oils are the same; after the test, there is no carbon deposits on the engine pistons. But the possibility of deposit formation is determined by the volatility of the liquid; it is characterized by the flash point of the oil. ZIC takes the lead: the specified parameter is 242 0C.

Characteristics of SAE 10w 40 engine oil

Recommended for four-stroke gasoline, diesel and gas engines, where oil of this particular viscosity is specified. Can be used in almost all areas (from light motor vehicles to special machines used in particularly difficult conditions).

Generalized data for semi-synthetics:

Stable viscosity - at 100°C mm²/s 14 DIN 51562 Pour point - °C -35 DIN ISO 3016

Stable viscosity - at 40°C mm²/s 91.3 DIN 51562 Viscosity index - 157 DIN ISO 2909 Total base number - mg KOH/g 7 DIN ISO 3771 Density at - 20°C kg/m³ 868 DIN EN ISO 12185 Sulphated ash — % 1.5 DIN 51575 Ignition temperature — °C 210 DIN ISO 2592 Color – brown

With the right choice of semi-synthetic motor oil SAE 10w 40, its use will ensure:

• Good compatibility with catalysts
• Low volatility
• Viscosity stability with temperature changes
• Permanent oil film under virtually all operating conditions
• Extended drain interval due to oxidation resistance
• No carbon deposits
• Engine cleanliness thanks to detergent and dispersant additive
• Fuel economy
• Wear protection

Nomination: engine protection under extreme conditions

Engine components in which friction forces act will be in extreme conditions if the engine is not filled with enough oil. Tribological indicators (friction, wear, the influence of lubrication in technical systems) determined the leaders at this stage.

The main objective of this test was to track the critical load: the stability of the oil film, to measure the radius of the wear scar, which makes it possible to evaluate the anti-wear characteristics of the motor fluid. All test participants showed good results. The ZIC brand has the lowest performance, but this will not significantly affect the operation of the power unit, because in real conditions such loads do not occur.

Mannol and Mobil are in the lead, with Shell slightly behind the favorites.

Oil selection

1. First of all, check the manufacturer's recommendations. This information is available in the operating manual. Most motors differ in design from each other. Manufacturers create a power unit taking into account a certain level of viscosity. How the oil flows throughout the engine is influenced by the power of the oil pump, the size of the passage channels, other features of the engine, the density of the lubricant, and its specific gravity. The wrong choice of car oil can lead to big problems.
2. The climate in which the machine is operated. Everything is pretty easy here. The stronger the frost, the more liquid the oil liquid should be. Mineral motor oil 15w40 is optimal for moderate climatic conditions.
3. The condition of the power unit into which lubricant will be poured. Such a factor as the degree of wear of engine elements is important. The consequence of wear of the contacting parts is an increase in the gaps between them. Liquid oil will simply flow away. Then you need to pour in a thicker product. The oil can even be mineral water; this will have almost no effect on the performance of the power unit. You will only need to replace the oil fluid more often.
4. Preservation of fuel or sporty driving style? Trying to save a couple of percent of fuel and filling in a low-viscosity lubricant, it is possible to break the engine if you do not take into account the tolerances specified in the operating manual.

We recommend: Technical characteristics of Idemitsu 5W-40 engine oil

Another example of incorrect selection is the use of a low-viscosity lubricant in a car used for racing driving. For such driving, it is much better to pour thicker oil, which forms a strong film between the contacting elements. It will protect engine parts from the consequences of sports driving.

Once you understand how oil markings are deciphered, you can immediately go and buy lubricant. 15w40 car oil is considered universal. High-temperature viscosity makes it possible to fill it if the temperature is less than plus forty degrees. Low-temperature viscosity allows you to use “magpie” if the street temperature is at least minus twenty degrees (pour point).

One misconception also needs to be mentioned. Many people believe that 10w40 oil is better than 15w40. This is not true. The viscosity class does not relate to the oil base; it does not depend on it whether the lubricant will be semi-synthetic or mineral. If the origin of the petroleum product is important to you, carefully read the label on the container. 10w40 is semi-synthetic, 15w40 is mineral water. 10w40 can be used over a wider temperature range.

Nomination: environmental friendliness of products

At this stage, the amount of toxic components is assessed, plus the content of aggressive substances in the motor fluid. Compounds of the latter, having penetrated the neutralizer, significantly reduce its service life.

In terms of residual hydrocarbons and nitrogen oxides, Castrol took the lead. The remaining oils have the same results. Shell, Esso, Mobil, Mannol have more of these combustion products.

The phosphorus content of all participants was satisfactory. The least amount of it is in ZIC, Castrol, Visco, Shell. The sulfur content in the participants is approximately 0.5%. The ZIC brand has a sulfur content of 0.19%.

According to the results of the competition, ZIC is in the lead.

What does the inscription SAE mean?

SAE (Society of Automotive Engineers - community of automotive engineers). They are the ones who set the regulations on viscosity for oils.

Let's look at, for example, SAE 10w40

10w – pour point (meaning preservation of fluidity at -30 ° C) The calculation is as follows: 40 - 10 = 30. In a word, this means how easily you can start a car in winter.

40 – this indicator is responsible for the density; this figure also contains an individual system for calculating viscosity stability at temperatures up to 150 ° C

Viscosities of the type 10w, 20w, 30w and others are called monoviscosity. Used in countries without significant temperature changes.

Pedestal

1-2 place

Shell Helix Plus

It won in the environmental friendliness and starting categories, has a high alkalinity number, and there is no carbon deposits on the pistons after testing it. Has the highest viscosity index.

Of the minuses: small critical load.

1-2 place

ZIC A+

Leads in the categories of environmental friendliness, start-up, and power. Low sulfur and phosphorus content, low toxicity of exhaust gases. Democratic price. Excellent starting qualities.

Of the minuses: did not take the lead during testing at the World Championships.

3rd place

Esso Ultra

Became one of the leaders in the efficiency category. Viscosity characteristics are close to optimal. Has a good price.

Of the minuses: does not affect power.

4th place

Mobil Super 2000 X1

The leader in the extreme conditions category. It has good tribological characteristics and affects the efficiency of the motor.

Disadvantages: high cost. Index SJ

5th place

Ravenol TSI

Didn't become a leader in any of the nominations. Characterized by a low pour point. Low phosphorus and sulfur content, highly environmentally friendly.

There is nothing to highlight among the minuses. The liquid is reliable without any pronounced advantages.

6th place

Castrol Magnatec

It has good energy-saving properties and a low content of toxic components in exhaust gases. It is better to fill it at high ambient temperatures.

Of the minuses: High cost. Low viscosity index, low wear rate.

7th place

Mannol Classic

It is characterized by a low pour point and high resistance of the oil film in extreme situations. Low cost.

Of the minuses: low energy savings.

8th place

BP Visco 3000

It has good protective properties under operating conditions at high loads and temperatures. Better to use in summer.

Of the minuses: starting properties at sub-zero temperatures are worse than those of competitors, does not affect fuel economy.

Effect of oils on engine starting

Lubricants with a low pour point create favorable conditions for starting the engine in winter. Starting performance is assessed by testing lubricants using a special device that simulates crankshaft rotation. This determines the dynamic viscosity of each lubricant at sub-zero temperatures.

With a viscosity index of more than 155, ZIC and Shell oils took leading positions. They freeze at a temperature of minus 35°C. Visco and Castrol oils showed the worst results - less than 147.

Originality and quality of lubricant is an important point when purchasing

Oil test before filling into the engine

One of the most important considerations for the buyer of modern lubricants is quality control. You can simply drain the old lubricant, fill in any substance purchased in bulk and drive for several hundred kilometers without problems.

But poor quality will definitely make itself felt. It is especially important what kind of oil you use for diesel engines. All the good characteristics of 10w40 oil are revealed if the following conditions are met:

• original packaging - it is extremely rare to find materials on tap with a sufficiently high quality of sales;
• checking a small part for solid inclusions, rubbing it on your fingers before pouring it into the engine;
• checking that there is no significant precipitation, otherwise it will turn into slag in the system of your power unit;
• inspection of packaging, independent opening, full confidence in the factory production of materials;
• reading the recommendations on the label, choosing exactly the oil that will be optimal for your car’s engine.

The selection includes not only the characteristics of viscosity and freezing of the liquid at certain temperatures. The problem of selecting lubricants is relevant for many motorists today.

Also read: Motor oil 5w30: characteristics

You need to choose a lubricant brand, look at the important parameters from the manufacturer, and read the requirements of the manufacturer of your car. Also, the price range is of great importance. Not all lubricants with 10w40 indexes have the necessary characteristics and capabilities.

How long can you drive on semi-synthetic oil?

The issue of operating this lubricant is quite complex. One specialist will say that such a lubricant does not last more than 8-10 thousand kilometers. But the properties of high-quality oil remain unchanged for a longer period.

It is worth adhering to the average recommendations. The oil mixture can last about 12-15 thousand kilometers or 1 year of operation. After one of these indicators occurs, it is worth replacing the technical fluid.

Determining a parameter using a hydrometer

This is how you check the oil level.
At home, the density of the lubricant can be determined using a hydrometer. It is a float - a sealed glass flask with ballast. It is equipped with a thermometer at the bottom and a density scale in a glass tube at the top.

1. Take measurements at oil temperature +20 °C.
2. Pour the mixture into a tall glass or plastic cylinder.
3. Carefully lower the clean and dry hydrometer into the liquid so that it does not touch the sides of the container.
4. Place the cylinder so that the desired value scale is at eye level.
5. Wait until the device stops oscillating.
6. Take readings. At the same time, measure the temperature of the liquid.

What to do if the temperature is not +20 degrees? In this case, the exact values ​​of the lubrication parameters can be determined from the table below. It shows them adjusted for temperature.

Antioxidant properties ↑

The high value of the antioxidant properties of motor oils determines its resistance to aging. Working in the aggressive operating environment of automobile engines, the oil is always subject to oxidation. As a result, it becomes viscous, loses density, promotes corrosion of engine elements, forms deposits on them, oil filters become clogged, and cold starting of the engine becomes impossible. It is possible to reduce the rate of oil oxidation by purifying its base raw materials from unnecessary impurities or using additives with antioxidant properties.

Density table for winter motor oils

Lubricants designated by the index 5w40–25w40 are classified as winter types (W - Winter). The density of such products varies in the range of 0.85–0.9 kg/l. The number in front of the “W” indicates the temperature at which the piston cylinders turn and turn. The second number is the viscosity index of the heated liquid. The density index of 5W40 class lubricant is the minimum among winter types - 0.85 kg/l at 5 °C. A similar product of the 10W40 class has a value of 0.856 kg/l, and for 15w40 the parameter is 0.89–0.91 kg/l.

The table shows that the indicator of winter mineral lubricants fluctuates at 0.867 kg/l. When operating lubricating fluids, it is important to monitor deviations in density parameters. An ordinary hydrometer will help you measure the value.

Let's sum it up

Engine lubrication principle

Now you not only know how the indices on cans of technical automotive fluids are deciphered, but you can also choose high-quality lubricants. A car needs high-quality maintenance, otherwise it will not be able to work for a long time and bring pleasure and reliability.

Engine operation is associated with constant friction and certain risks of increased wear. So, once incorrectly filled with oil, it can cause failure of quite expensive products and components of the unit.

In the middle and southern parts of our country there is no need to change oils for winter use. And in the northern regions, you should prepare your car for winter. To do this, it is important to purchase an oil that can withstand all the required temperatures.

If you make the wrong choice, you may find yourself in an unpleasant situation when the next morning the car refuses to start. But this problem can also be solved by simply installing a pre-heater in the crankcase. The oil in your car must be of high quality and fully perform its main tasks.